Increase of neurofilament-H protein in sensory neurons in antiretroviral neuropathy: Evidence for a neuroprotective response mediated by the RNA-binding protein HuD.

Nucleoside reverse transcriptase inhibitors (NRTIs) are key components of HIV/AIDS treatment to reduce viral load. However, antiretroviral toxic neuropathy has become a common peripheral neuropathy among HIV/AIDS patients leading to discontinuation of antiretroviral therapy, for which the underlying pathogenesis is uncertain. This study examines the role of neurofilament (NF) proteins in the spinal dorsal horn, DRG and sciatic nerve after NRTI neurotoxicity in mice treated with zalcitabine (2',3'-dideoxycitidine; ddC). ddC administration up-regulated NF-M and pNF-H proteins with no effect on NF-L. The increase of pNF-H levels was counteracted by the silencing of HuD, an RNA binding protein involved in neuronal development and differentiation. Sciatic nerve sections of ddC exposed mice showed an increased axonal caliber, concomitantly to a pNF-H up-regulation. Both events were prevented by HuD silencing. pNF-H and HuD colocalize in DRG and spinal dorsal horn axons. However, the capability of HuD to bind NF mRNA was not demonstrated, indicating the presence of an indirect mechanism of control of NF expression by HuD. RNA immunoprecipitation experiments showed the capability of HuD to bind the BDNF mRNA and the administration of an anti-BDNF antibody prevented pNF-H increase. These data indicate the presence of a HuD - BDNF - NF-H pathway activated as a regenerative response to the axonal damage induced by ddC treatment to counteract the antiretroviral neurotoxicity. Since analgesics clinically used to treat neuropathic pain are ineffective on antiretroviral neuropathy, a neuroregenerative strategy might represent a new therapeutic opportunity to counteract neurotoxicity and avoid discontinuation or abandon of NRTI therapy.

Spinal RyR2 pathway regulated by the RNA-binding protein HuD induces pain hypersensitivity in antiretroviral neuropathy.

The antiretroviral toxic neuropathy, a distal sensory polyneuropathy associated with antiretroviral treatment, is a frequently occurring neurological complication during treatment of patients with AIDS and often leads to discontinuation of antiretroviral therapy. The mechanisms by which antiretroviral drugs contribute to the development of neuropathic pain are not known. Using drugs that reduce intracellular calcium ions (Ca(2+)), we investigated the hypothesis that altered cytosolic Ca(2+) concentration contributes to the 2',3'-dideoxycytidine (ddC)-evoked painful neuropathy. Administration of ddC induced mechanical and cold allodynia, which were abolished by intrathecal administration of TMB-8, a blocker of Ca(2+) release from intracellular stores, and by ryanodine, a RyR antagonist. Treatment with the IP3R antagonist heparin prevented mechanical allodynia with no effect on thermal response. To further clarify the pathway involved, we investigated the role of HuD, a RNA binding protein involved in neuronal function. HuD silencing reverted both mechanical and cold allodynia inducing, a phenotype comparable to that of ryanodine-exposed mice. HuD binding to the RyR2 mRNA, the most abundant RyR isoform in the spinal cord, was demonstrated and RyR2 silencing prevented the ddC-induced neuropathic pain. A positive regulation of gene expression on CaMKIIα by HuD was also observed, but sequestration of CaMKIIα had no effect on ddC-induced allodynia. The present findings identify a spinal RyR2 pathway activated in response to ddC administration, involving the binding activity on RyR2 mRNA by HuD. We propose the modulation of the RyR2 pathway as a therapeutic perspective in the management of antiretroviral painful neuropathy.

The RNA-binding protein HuD promotes spinal GAP43 overexpression in antiretroviral-induced neuropathy.

Nucleoside reverse transcriptase inhibitors (NRTIs) are known to produce painful neuropathies and to enhance states of pain hypersensitivity produced by HIV-1 infection in patients with AIDS leading to discontinuation of antiretroviral therapy, thus limiting viral suppression strategies. The mechanisms by which NRTIs contribute to the development of neuropathic pain are not known. In the current study, we tested the hypothesis that HuD, an RNA binding protein known to be an essential promoter of neuronal differentiation and survival, might be involved in the response to NRTI-induced neuropathy. Antiretroviral neuropathy was induced by a single intraperitoneal administration of 2',3'-dideoxycytidine (ddC) in mice. HuD was physiologically expressed in the cytoplasm of the soma and in axons of neurons within DRG and spinal cord and was considerably overexpressed following ddC treatment. ddC up-regulated spinal GAP43 protein, a marker of neuroregeneration, and this increase was counteracted by HuD silencing. GAP43 and HuD colocalize in DRG and spinal dorsal horn (SDH) axons and administration of an anti-GAP43 antibody aggravated the ddC-induced axonal damage. The administration of a protein kinase C (PKC) inhibitor or the PKCγ silencing prevented both HuD and GAP43 increased expression. Conversely, treatment with the PKC activator PDBu potentiated HuD and GAP43 overexpression, demonstrating the presence of a spinal PKC-dependent HuD-GAP43 pathway activated by ddC. These results indicated that HuD recruitment and GAP43 protein increase are mechanistically linked events involved in the response to antiretroviral-induced neurodegenerative processes.

PKC-mediated HuD-GAP43 pathway activation in a mouse model of antiretroviral painful neuropathy.

Patients treated with nucleoside reverse transcriptase inhibitors (NRTIs) develop painful neuropathies that lead to discontinuation of antiretroviral therapy thus limiting viral suppression strategies. The mechanisms by which NRTIs contribute to the development of neuropathy are not known. In order to elucidate the mechanisms underlying this drug-induced neuropathy, we have characterized cellular events in the central nervous system following antiretroviral treatment. Systemic administration of the antiretroviral agent, 2',3'-dideoxycytidine (ddC) considerably increased the expression and phosphorylation of protein kinase C (PKC) γ and ɛ, enzymes highly involved in pain processes, within periaqueductal grey matter (PAG), and, to a lesser extent, within thalamus and prefrontal cortex. These events appeared in coincidence with thermal and mechanical allodynia, but PKC blockade did not prevent the antiretroviral-induced pain hypersensitivity, ruling out a major involvement of PKC in the ddC-induced nociceptive behaviour. An increased expression of GAP43, a marker of neuroregeneration, and decreased levels of ATF3, a marker of neuroregeneration, were detected in all brain areas. ddC treatment also increased the expression of HuD, a RNA-binding protein target of PKC known to stabilize GAP43 mRNA. Pharmacological blockade of PKC prevented HuD and GAP43 overexpression. Silencing of both PKCγ and HuD reduced GAP43 levels in control mice and prevented the ddC-induced GAP43 enhanced expression. Present findings illustrate the presence of a supraspinal PKC-mediated HuD-GAP43 pathway activated by ddC. Based on our results, we speculate that antiretroviral drugs may recruit the HuD-GAP43 pathway, potentially contributing to a response to the antiretroviral neuronal toxicity.

Advanced MRI morphologic study shows no atrophy in healthy individuals with hippocampal hyperintensity.

We have already shown that brain MR imaging of healthy individuals frequently reveals either unilateral or bilateral Hh, which is considered a hallmark of hippocampal sclerosis. We performed a follow-up (5-year interval) clinical and advanced imaging study of these individuals to address whether Hh may have masked occult brain atrophy or contributed to a later onset of epilepsy. Subjects with Hh (n = 13) underwent a detailed clinical-imaging protocol, with a 3T scan and were studied with automated hippocampal segmentation (FreeSurfer), whole brain voxel-based morphometry, and shape analysis. All 13 subjects with Hh had normal neurologic examination findings with no cognitive impairment. Multimodal structural neuroimaging methods did not show clear evidence of significant volumetric changes between subjects with or without Hh. We clearly showed that Hh is not associated with any occult brain atrophy; furthermore, none of the healthy subjects with MR imaging evidence of Hh developed epilepsy or trouble with cognition.

Usefulness of rectal biopsy for the diagnosis of Kufs disease: a controlled study and review of the literature.

BACKGROUND AND PURPOSE: Rectal biopsy is usually performed for in vivo diagnosis of Kufs disease (KD). We evaluated the usefulness of rectal biopsy in the diagnosis of such condition by comparing ultrastructural data of patients with suspicion of KD with those of control subjects. Furthermore, we reviewed literature data concerning the value of such a diagnostic procedure in the diagnosis of KD. METHODS: Sixty-five subjects were enrolled and underwent rectal biopsy. Of these, 13 had a clinical picture in keeping with KD, whereas 52, affected by Irritable Bowel Syndrome, constituted the control group. RESULTS: Ultrastructural analysis evidenced fingerprint (FP) inclusions in 12 subjects, 4/13 with suspicion of KD and 8/52 controls. In patients, FPs were mainly located in vascular smooth muscle cells (VSMC) while in controls they were mostly found in pericytes and VSMC. No FPs were found in one patient with genetically confirmed KD. In literature, we identified 14 KD patients who underwent rectal biopsy. In most reports, ultrastructural features were not systematically analyzed or described. CONCLUSIONS: Fingerprints are the most common ultrastructural finding in rectal biopsy in patients with suspicion of KD. However, their presence in pericytes and VSMC is not specific for KD because they may be found in controls subjects. Our literature review revealed that data on the value of rectal biopsy in the diagnosis of KD are scarce. In light of these findings, the relevance of rectal biopsy in such condition should be re-evaluated.

Abnormal pressure waves in headache sufferers with bilateral transverse sinus stenosis.

INTRODUCTION: Bilateral transverse sinus stenosis (BTSS) has been reported to be associated with idiopathic intracranial hypertension without papilloedema in headache sufferers. SUBJECTS AND METHODS: To test the accuracy of short-term cerebrospinal fluid (CSF) pressure monitoring through a lumbar needle for detection of elevated intracranial pressure in headache sufferers with BTSS, we prospectively performed lumbar puncture in order to measure lumbar CSF opening pressures and to monitor, for 1 h, the CSF pressure in 48 consecutive headache sufferers with BTSS and in 50 consecutive headache sufferers with normal appearance of transverse sinuses or stenosis of one transverse sinus. RESULTS: Of the 48 headache sufferers with BTSS, 18 (37.5%) had elevated CSF opening pressure and abnormal pressure waveforms, but short-term CSF pressure monitoring revealed abnormal pressure waves associated with elevated mean CSF pressure also in 26 (86.6%) out of 30 patients who had normal opening pressures. None of the 50 headache sufferers with normal appearance of transverse sinuses or stenosis of one transverse sinus had abnormal pressure waves and elevated CSF pressures. CONCLUSIONS: In this study, short-term CSF pressure monitoring through a lumbar needle revealed abnormal pressure waves and elevated mean CSF pressures in the majority of headache sufferers with BTSS who had normal CSF opening pressures. These findings demonstrate the accuracy of short-term CSF pressure monitoring through a lumbar needle in estimating CSF pressure; they also highlight that a single-spot opening pressure measurement has a low accuracy for recognition of increased intracranial pressure in headache sufferers with BTSS.

DJ-1 is a Parkinson's disease susceptibility gene in southern Italy.

Mutations in the gene DJ-1 have been shown to be a rare cause of early-onset Parkinson's disease (EOPD). Since DJ-1 mutations have been found in patients with Parkinson's disease (PD) from southern Italy, we aimed to investigate whether polymorphisms within the DJ-1 gene could represent a risk factor for sporadic PD. First, we genotyped 294 patients with PD and 298 controls coming from southern Italy to assess the distribution of the insertion/deletion (Ins/Del) polymorphism. In a second phase, we identified five single-nucleotide polymorphisms (SNPs) useful to delimit a region potentially involved and genotyped all patients and controls for these markers. All the markers analyzed were significantly associated with PD at both allelic and genotypic level. The most significant association with the disease was found at the Ins/Del polymorphism (p = 0.0001; adjusted odds ratio (OR ) = 2.05; confidence interval (CI ) = 1.36-3.08). When we considered a three-marker sliding window, we found a highly significant association between the disease and the haplotypes including markers rs17523802, Ins/Del, and rs3766606 (p = 0.0007) and markers Ins/Del, rs3766606 and rs7517357 (p = 0.0054). Our results indicate that polymorphisms located in a region spanning 3535 bp from the promoter to the intron 2 of the DJ-1 gene confer risk to sporadic PD in southern Italy.

CADASIL: extended polymorphisms and mutational analysis of the NOTCH3 gene.

CADASIL is a cerebrovascular disease caused by mutations in the NOTCH3 gene. Most mutations result in a gain or loss of cysteine residue in one of the 34 epidermal growth factor-like repeats in the extracellular domain of the Notch3 protein, thus sparing the number of cysteine residues. To date, more than 130 different mutations in the NOTCH3 gene have been reported in CADASIL patients, of which 95% are missense point mutations. Many polymorphisms have also been identified in the NOTCH3 coding sequence, some of them leading to amino acid substitutions. The aim of the present study was to analyze the NOTCH3 gene in a large group of patients affected by leukoencephalopathy and to investigate the presence of genetic variants. The molecular analysis revealed several nucleotide alterations. In particular, we identified 20 different mutations, 22 polymorphisms, and 8 genetic variants of unknown pathological significance never reported previously. We hope that this NOTCH3 gene mutational analysis, performed in such a significant number of unrelated and related patients affected by leukoencephalopathy, will help in molecular screening for the NOTCH3 gene, thus contributing to enlargement of the NOTCH3 gene variation database.

Bilateral transverse sinus stenosis and idiopathic intracranial hypertension without papilledema in chronic tension-type headache.

Previous MR studies have established that bilateral transverse sinus stenosis (BTSS) predicts idiopathic intracranial hypertension without papilledema (IIHWOP) in migraine. However, it is uncertain whether BTSS identifies IIHWOP in patients with chronic tension-type headache (CTTH): using cerebral MR venography this study aimed to address this question.In a prospective study from February 2002 to December 2006, 198 consecutive patients with CTTH underwent MR venography. Of these patients, 58 underwent lumbar puncture to measure cerebrospinal fluid (CSF) pressure. MR venography and lumbar puncture were also performed in 45 age-matched control subjects. BTSS was considered present when the signal flow was poor or lacking (flow gap) in the mid-lateral portion of both transverse sinuses. IIHWOP was diagnosed if the patient met the diagnostic criteria for idiopathic intracranial hypertension and did not have papilledema. Among the 198 patients with CTTH who underwent MR venography, 18 (9%) had BTSS. Thirteen of these 18 patients with BTSS underwent lumbar puncture, and nine (69.2%) had IIHWOP. CSF opening pressure was normal in all 45 patients as well as in all 45 controls with normal MR venography.These data suggest that BTSS on MR venography is associated with increased intracranial pressure in the absence of papilledema in patients with headache mimicking CTTH.

Hyperhomocysteinemia is associated with cognitive impairment in multiple sclerosis.

Hyperhomocysteinemia (HHcy) has been associated with cognitive impairment in various neurological diseases. Cognitive impairment occurs early in multiple sclerosis (MS). Conflicting data have been reported regarding plasma total homocysteine (tHcy) levels in MS patients, and the impact of HHcy on cognitive impairment in MS is not known. This study investigated whether plasma total homocysteine levels are increased in MS and if HHcy is associated with cognitive impairment in MS. We compared tHcy levels in 94 patients with MS and 53 healthy age-matched controls. We used a neuropsychological test battery that included the Raven's Coloured Progressive Matrices, the Visual Search Test, the Trail Making Test A and B, the Immediate and Delayed Recall of a Short Story, the 30 Paired Word Associates, the Rey-Osterrieth Complex Figure Test, and the Semantic and Verbal Fluency Tests. Clinical (sex, age, type of MS, relapse, disease duration, coexisting disease, smoking habit, and physical disability) and laboratory variables (HHcy, low serum levels of folate and vit.B12, MTHFR genotype) were evaluated for their ability to predict cognitive impairment. The mean tHcy was higher in patients (13.19 micromol/L, SD5.58) than in controls (9.81 micromol/L, SD2.53; p < 0.001). Univariate analysis determined the following factors to be associated with cognitive impairment: higher age at observation, chronic progressive course of disease, longer disease duration,moderate or severe physical disability, and frequency of HHcy. With multivariate regression analysis, there remained a significant association only between frequency of HHcy and cognitive impairment (beta 0.262, p = 0.01). We conclude that tHcy levels are increased in MS and that HHcy is associated with cognitive impairment in this disease.

Defining a neuron: neuronal ELAV proteins.

Neuronal cells strongly depend on the control exerted by RNA-binding proteins (RBPs) on gene expression for the establishment and maintenance of their phenotype. Neuronal ELAV (nELAV) proteins are RBPs able to influence virtually every aspect of the postsynthesis fate of bound mRNAs, from polyadenylation, alternative splicing and nuclear export to cytoplasmic localization, stability and translation. They enhance gene expression through the last two, best documented activities, increasing mRNA half-life and promoting protein synthesis by a still-unknown molecular mechanism. Developmentally, nELAV proteins have been shown to act as inducers of the transition between neural stem/progenitor cells and differentiation-committed cells, also assisting these neuroblasts in the completion of their maturation program. In brain physiology, they are also the first RBPs demonstrated to have a pivotal role in memory, where they probably control mRNA availability for translation in subcellular domains, thereby providing a biochemical means for selective increase in synaptic strength.

Bilateral transverse sinus stenosis predicts IIH without papilledema in patients with migraine.

BACKGROUND: The headache profile of patients with idiopathic intracranial hypertension without papilledema (IIHWOP) may be indistinguishable from that of migraine. Bilateral transverse sinus stenosis (BTSS) has been found in the majority of patients with IIHWOP. The frequency of BTSS associated with IIHWOP in patients with migraine is unknown. OBJECTIVE: To detect the frequency of BTSS in adult patients with migraine and to investigate whether the presence of BTSS identifies patients with IIHWOP. METHODS: In a prospective study from December 2000 to November 2005, 724 consecutive patients with recurrent headaches who fulfilled International Headache Society diagnostic criteria for migraine underwent cerebral MR venography (MRV). A portion of these patients underwent a lumbar puncture (LP) to measure CSF pressure. MRV and LP were also performed in 70 age-matched control subjects. RESULTS: Six hundred seventy-five of the 724 patients with migraines had normal MRV. Seventy of these 675 patients underwent LP, and all of them had normal CSF pressure. Forty-nine (6.7%) of the 724 patients with migraine had BTSS. Twenty-eight of these 49 patients with BTSS underwent LP, and 19 (67.8%) had IIHWOP. The headache profiles of patients with BTSS and IIHWOP did not differ from those of patients with normal MRVs and CSF pressures within normal limits. CSF pressure was normal in both patients and controls with normal MRV. CONCLUSIONS: Of patients with migraine, 6.7% had bilateral transverse sinus stenosis; 67.8% of these patients had idiopathic intracranial hypertension without papilledema (IIHWOP). These results suggest that patients with migraine who present bilateral transverse sinus stenosis on cerebral MR venography should undergo lumbar puncture to exclude IIHWOP.

The spectrum of Notch3 mutations in 28 Italian CADASIL families.

BACKGROUND: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is a cause of hereditary cerebrovascular disease. It results from mutations in the Notch3 gene, a large gene with 33 exons. A cluster of mutations around exons 3 and 4 was originally reported and limited scanning of these exons was suggested for the diagnosis in most cases. OBJECTIVE: To report Notch3 mutation analysis in 28 unrelated Italian CADASIL families from central and south Italy. RESULTS: The highest rate of mutations was found in exon 11 (21%) and only 18% of mutations were in exon 4. This may be related to the peculiar distribution of Notch3 mutations in the regions of origin of the families. CONCLUSIONS: The results suggest that limited scanning of exons 3 and 4 is inadvisable in CADASIL cases of Italian origin.

Clinical and muscle magnetic resonance imaging study of an Italian family with autosomal dominant inclusion body myopathy not linked to known genetic loci.

The objective was to report a clinical, pathological and muscle magnetic resonance (MR) study of an Italian family with an autosomal dominant inclusion body myopathy (AD-IBM). Eight subjects (age range 20-56 years; 5 females and 3 males) belonging to four generations were studied. Onset of disturbances (distal weakness at lower limbs) ranged from 20 to 28 years. CK levels were increased to five times. Only in an early stage oedema of involved muscles has been demonstrated by muscle MR. Quadriceps femoris was characteristically spared; in the last phases a mild involvement of the vasti became evident with persistent sparing of the rectus femori. Rimmed vacuoles and hyperphosphorylated tau filaments were evident at muscle biopsy. Linkage analysis excluded the association of the disease to chromosome loci 14q11, 17p13.1, 2p13, 19p13. The study suggests that quadriceps sparing is a characteristic feature also of AD-IBM. This finding could represent a muscle-image hallmark helpful in diagnosis of autosomal dominant muscular disorders.

A novel Notch3 gene mutation not involving a cysteine residue in an Italian family with CADASIL.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary cerebrovascular disease leading to accumulating neurologic deficits and dementia. CADASIL has been linked to nucleotide substitutions and deletions in the Notch3 gene. All the mutations described until now lead to unpaired cysteine residue in the epidermal growth factor-like repeats. The authors report a family with CADASIL carrying a deletion in the Notch3 gene that did not involve a cysteine residue.

Suggestive evidence for linkage to chromosome 13qter for autosomal dominant type 1 porencephaly.

A large three-generation family with autosomal dominant type 1 porencephaly from southern Italy was studied. A high rate of miscarriages was observed. Of the nine affected individuals, four displayed a severe phenotype, and five had slight pyramidal signs or mild cognitive abnormalities. The MRI study disclosed unilateral porencephalic cyst, or colpocephaly. A genome-wide screen resulted in suggestive evidence for linkage to chromosome 13qter with a maximum logarithm-of-the-odds score of 3.16, from multipoint analysis, with marker D13S285.