L’existence de douleurs neuropathiques et/ou de perte de la sensibilité douloureuse sont souvent le reflet d’une neuropathie sensitive affectant plus particulièrement les fibres nerveuses sensitives amyélinique Aδ et C, dites neuropathie des petites fibres (NPF). Ces fibres innervent, notamment, le derme et l’épiderme de la peau. Elles communiquent la sensibilité thermique et algique au système nerveux central et contribuent à l’homéostasie cutanée, entre autres, par la libération de neuropeptides en périphérie. De nombreuses pathologies sont associées à une altération de ces petites fibres dans la peau. Deux pathologies impliquant une NPF ont été étudiées au cours de ce travail : les escarres et la maladie de Charcot-Marie-Tooth type 1A. Un travail expérimental a été réalisé chez la souris pour répondre à la question suivante ; est-ce qu’une seule atteinte des fibres nociceptives, responsables de la perte de sensibilité peut entraîner un déséquilibre de l’homéostasie cutanée, responsable de l’apparition des escarres ? La mise en place d’un modèle de neuropathie sensitive fonctionnelle réversible a permis de mettre en en évidence l’implication des neuropeptides, substance P (SP) et « calcitonin gene-related peptide » (CGRP), libérés par les fibres nerveuses cutanées, dans la formation d’ulcères de pression. Un traitement préventif à la rhEPO (Recombinant Human Erythropoietin) dans ce modèle associant une neuropathie et des plaies de pression, protège la peau contre une pression ischémiante induisant une escarre par son effet neuroprotecteur sur les petites fibres cutanées. L’association CMT1A et NPF a été étudiée à partir de biopsies cutanées humaines. La quantification des fibres intraépidermiques révèle que 48% des patients CMT1A sont atteints d’une NPF. L’analyse des biopsies cutanées révèle également une altération du nombre et de la morphologie de cellules de Langerhans dans la maladie de CMT1A. L'ensemble de ces résultats confirme l'intérêt de l'étude des petites fibres dans des pathologies variées et confirme le potentiel thérapeutique neuroprotecteur de l'EPO / The neuropathic pain and/or hypoalgesia often reflect a sensory neuropathy that affects particularly sensory, Aδ (thinly myelinated) and C (unmyelinated) nerve fibers. This kind of neuropathy is named "small fiber neuropathy" (SFN). These small fibers innervate the dermis and epidermis. C and Aδ free nerve endings respond to a variable range of stimuli including mechanical, thermal and pain stimuli. They conduct nociceptive signals to central nervous system and contribute to skin homeostasis, among others, by the release of neuropeptides in the periphery. Many diseases are associated with an alteration of these cutaneous small fibers. Two pathologies involving SFN were studied in this work: pressure ulcers and Charcot-Marie-Tooth disease Type 1A (CMT1A). Experimental studies on mice were performed to determine if impairment of nociceptive fibers could lead to an imbalance of skin homeostasis and could be involved in development of pressure ulcers, apart from its role in pain signal transduction. A functional reversible sensory neuropathy mouse model was set up and helped to demonstrate the involvement of the neuropeptides, substance P (SP) and "calcitonin gene-related peptide" (CGRP), released by cutaneous nerve fibers in the formation of pressure ulcers. By its neuroprotective effect on small nerve fibers, a preventive rhEPO (Recombinant Human Erythropoietin) treatment in this model protects the skin against an ischemic pressure-induced Stage 2 ulcer. The CMT1A and SFN association has been studied from human skin biopsies. Quantification of intraepidermal nerve fibers reveals that 48% of CMT1A patients have a SFN. The analysis of skin biopsies also revealed an alteration in the number and morphology of Langerhans cells in CMT1A disease. All these results confirm the interest of the study of small fibers in various pathologies and confirm the neuroprotective therapeutic potential of EPO.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Charcot-Marie-Tooth (CMT) disease is the most common genetically determined neurological condition in the world. It is characterized by a slow and progressive degeneration of the peripheral nerves, leading to weakness and atrophy of distal limb muscles. CMT is classified in two main subgroups: CMT type 1 (CMT1), demyelinating form, and CMT type 2 (CMT2), axonal form. The first objective of this study was to conduct a systematic review of the prevalence of CMT disease in the world and the second was to evaluate the epidemiological, socio-demographic and psychosocial profile of families with CMT disease in the State of Sergipe, Brazil. Methods: a systematic survey of the literature was carried out using the following databases: MEDLINE-PubMed, Web of Science, Scopus and CINAHL (January 1990 to May 2015). Apart from this, a descriptive, observational and cross-sectional epidemiological study was carried out by means of interview and clinical evaluation of patients with the disease (CMT Group or CMTG) and non-affected family members called the control group (CG) in the municipalities of Tobias Barreto, Pedrinhas and Itabaianinha - SE. The collection of data included evaluation of socio-demographic characteristics, anthropometric measurements, lifestyle, clinical conditions, co-morbidities, mental health (levels of anxiety and depression), standards of feminine sexual behavior and gynecological and obstetric profiles. Results: in article 1, 12 studies were included in the systematic review, where the prevalence of CMT varied from 9.7/ 100,000 inhabitants in Serbia to 82.3/ 100,000 in Norway. The frequency of the main subtypes in the countries varied from 37.6% to 84% for CMT1 and from 12% to 35.9% for CMT2. In article 2, 90 individuals from 6 families with CMT were interviewed; the prevalence of CMT in Sergipe was of 62/ 100,000 inhabitants; the prevalence of CMT1 was of 37/ 100,000 inhabitants and of CMT2 was of 25/ 100,000. The majority presented the onset of signs and symptoms in childhood. There was a greater incidence of illiteracy among those affected, with a significant difference between the groups CMTG (19.5%) and CG (6%). Elevated levels of anxiety and depression were observed. Changes in sexual activity were observed in 47% of the women. Of these, 88% related to rarely or never use condoms; the most used contraceptive methods were oral and injectable contraceptives; as to fertility, the CG had on average 1.93 children, while the CMTG had on average 2.47 children. Conclusion: the results reveal the gaps, which still exist in the epidemiological knowledge of CMT across the world. The high prevalence of CMT in Sergipe, the elevated index of illiteracy among the individuals presenting signs and symptoms of CMT and the shorter reproductive cycle of women with CMT indicate the impact of the disease in the state. Future research is needed with a focus on the epidemiological characteristics of CMT in different nations and ethnic groups. / A doença de Charcot-Marie-Tooth (CMT) é a afecção neurológica geneticamente determinada mais comum em todo o mundo. Caracteriza-se por provocar degeneração lenta e progressiva dos nervos periféricos, acarretando fraqueza e atrofia dos músculos distais dos membros. CMT é classificada em dois subgrupos principais: CMT tipo 1 (CMT1), forma desmielinizante e CMT tipo 2 (CMT2), forma axonal. O primeiro objetivo deste estudo foi realizar uma revisão sistemática sobre a prevalência da doença de CMT no mundo e o segundo foi avaliar o perfil epidemiológico, sociodemográfico e psicossocial de famílias com a doença de CMT no Estado de Sergipe, Brasil. Métodos: pesquisa sistemática na literatura foi realizada, utilizando como base de dados a MEDLINE-PubMed, Web of Science, Scopus e CINAHL (janeiro de 1990 a maio de 2015). Além disso, foi realizado estudo epidemiológico descritivo, observacional e transversal, por meio de entrevista e avaliação clínica de pacientes, grupo com a doença CMT (GCMT), e familiares não afetados, denominados de grupo controle (GC), nos municípios de Tobias Barreto, Pedrinhas e Itabaianinha- SE. A coleta de dados incluiu avaliação das características sociodemográficas, parâmetros antropométricos, hábitos de vida, condições clínicas, comorbidades, saúde mental (níveis de ansiedade e depressão), padrão de comportamento sexual feminino e perfis ginecológicos e obstétricos. Resultados: no artigo 1, doze estudos foram incluídos na revisão sistemática, cuja prevalência de CMT variou de 9,7/ 100.000 habitantes, na Sérvia, para 82,3/ 100.000, na Noruega. A frequência dos principais subtipos nos países variou de 37,6% a 84% CMT1 é de 12% para 35,9% CMT2. No artigo 2, foram entrevistados 90 indivíduos de seis famílias com CMT; a prevalência de CMT em Sergipe foi de 62/ 100.000 habitantes; a prevalência CMT1 foi de 37/ 100.000 habitantes e CMT2 foi de 25/ 100.000. A maioria apresentou início do surgimento dos sinais e sintomas na infância. Houve maior índice de analfabetismo entre os afetados, com diferença significativa entre os grupos GCMT (19,5%) e GC (6%). Foram observados elevados níveis de ansiedade e depressão. Verificou-se alteração na atividade sexual em 47% das mulheres, das quais 88% relataram o uso de preservativo raramente ou nunca; os métodos contraceptivos mais utilizados foram os anticoncepcionais orais e injetáveis; em relação à fecundidade, o GC apresentou média de 1,93 filho, enquanto o GCMT obteve média de 2,47 filhos. Conclusão: os resultados revelam as lacunas que ainda existem no conhecimento epidemiológico de CMT em todo o mundo. A alta prevalência de CMT em Sergipe, o elevado índice de analfabetismo entre os indivíduos que apresentam os sinais e sintomas de CMT e o ciclo reprodutivo das mulheres CMT mais curto indicam o impacto da doença no Estado. São necessárias pesquisas futuras com foco em características epidemiológicas de CMT em diferentes nações e grupos étnicos.

Die Charcot-Marie-Tooth Typ 1 Erkrankungen sind eine genetisch heterogene Gruppe, aktuell nicht kurativ therapierbarer, erblicher Neuropathien des Peripheren Nervensystems. Klinische Manifestationen reichen von Sensibilitäts-störungen, verminderten Muskeleigenreflexen, sowie fortschreitenden Lähmungen, bis hin zu Muskelatrophie und bedeuten für die betroffenen Patienten eine starke Einschränkung der Lebensqualität. Anhand früherer Studien wurde Makrophagen, als Teil des angeborenen Immunsystems, eine entscheidende Rolle in der Pathogenese dreier CMT1-Unterformen zugeschrieben. Abgesehen von den morphologischen Manifestationen der demyelinisierenden CMT1-Erkrankungen, wie simultanes Auftreten von Dedifferenzierung, sowie Hypo-, und Demyelinisierung erkrankter Schwann-Zellen, sind pathologische Veränderungen der Domänengliederung der Ranvier’schen Schnürringe betroffener Nervenfasern ebenfalls von der Aktivierung pathogener Makrophagen abhängig. Auf der Basis verschiedener veröffentlichter Studien, welche sowohl demyelinisierende Erkrankungen des ZNS, aber auch primär durch axonale Schäden gekennzeichnete Erkrankungen des PNS beinhalten, besteht ein möglicher räumlicher Zusammenhang zwischen Architekturstörungen der RS und aktivierten pathogenen Mikrogliazellen bzw. Makrophagen. In dieser Studie konnte, anhand morphologischer Analysen von peripherem Nervengewebe, in Wt-Mäusen erstmals eine unerwartete präferentielle Lokalisation von Makrophagen im räumlichen Umfeld von RS beobachtet werden. Hierbei scheint, trotz des Fehlens einer direkten Zell-Zell-Interaktion zwischen Makrophagen und RS, vor allem im Hinblick auf die ebenfalls im räumlichen Umfeld von RS nachweisbare EZM und Fibroblasten, eine funktionelle Relevanz der assoziierten Makrophagen für die Aufrechterhaltung der Domänengliederung bzw. elektrophysiologischen Eigenschaften myelinisierter peripherer Nervenfasern denkbar. Im Gegensatz dazu wurde trotz der signifikanten Zunahme der Makrophagenanzahlen in den drei untersuchten CMT1-Mausmodellen keine erhöhte räumliche Assoziation mit den RS der mutierten Schwann-Zellen beobachtet. Vielmehr konnten anhand des Vergleiches mit wildtypischen Kontrollmäusen signifikant erniedrigte Assoziationsraten beider Strukturen in den CMT1-Modelltieren festgestellt werden. Folglich scheint die von der Einwanderung und Aktivierung pathogener Makrophagen abhängige Störung der Domänengliederung der RS der mutierten Schwann-Zellen, nicht durch eine direkte Interaktion bzw. räumliche Assoziation von Makrophagen mit RS ausgelöst zu werden. / The Charcot-Marie-Tooth neuropathies are a heterogenous group of inherited neuropathies oft he peripheral nervous system currenly incurable. Clinical symptoms vary from sensory loss, reduced tendon reflexes, muscular atrophy to progressive disability. According to different studies macrophages, as a part oft he innate immune system, play a crucial role in the pathogenesis of three different CMT-1 subtypes. Apart from morphological changes like dedifferentiation as well as hypo- and demyelination of diseased Schwann-cells, pathological alterations of nodes of Ranvier are also driven by activated marophages. As already described for demyelinating disoders oft he CNS, as well as neruodegenerative disorders oft he PNS, we investigated the spatial association of macrophages with diseased nodes of Ranvier. According to morphological analysis of peripheral nerve tissue this study is the first to describe an unexpected preferential spatial localization of macrophages near nodes of Ranvier in healthy nerves. Despite direct cell-cell interactions macrohages might play a functional role regarding the turnover of ECM and fibroblasts surrounding nodes of Ranvier, as well as the maintenance oft he architecture and electrophysiological features of peripheral nerve fibers.

No description available.

The aim of this 4 year long work was to study the Connexin32 (Cx32), a protein that forms hemichannels anchored in the plasma membrane. Two hemichannels of adjacent cells form a gap junction. Mutations in Cx32 have been associated to the X-linked form of Charcot-Marie-Tooth disease, a neurodegenerative illness affecting the peripheral nervous system. Cx32 is expressed in Schwann cells, in the paranodal zones. Using Xenopus laevis oocytes to express Cx32 hemichannels, we have monitored simultaneously the release of ATP and the ionic currents. ATP in the medium was detected with luciferin-luciferase reaction and the ionic currents were recorded under two electrode voltage clamp. Depolarization of oocytes expressing Cx32, from -40mV to +80mV induced an outward current and at the end of the pulse a transitory peak of ATP release. Using Cx32 transfected HeLa cells, we captured the luminescence due to ATP release, when cells were under a hypotonic solution containing luciferin-luciferase mixture. Isotonic solution was 280 mOsm and hypotonic solution was 150 mOsm. We also studied the release of ATP in Schwann cell cultures and again the hypotonic conditions induced a rapid increase of extracellular ATP. Finally, when we repeated the voltage clamp experiments expressing Cx32 and also syntaxin 1A, we saw a partial inhibition that of the currents and the release of ATP, which didn't happen when we repeated the hypotonic shock with HeLa cells expressing Cx32 and syntaxin. In order to keep on working in the ATP release through Cx32 hemichannels and its relation with CMT disease five different mutation already described in CMTX patients were generated in the lab, to study the ATP release through Cx32 mutated hemichannels in TEVC experiments with oocytes and transfecting mammal cells. This last part is not finished but it is conyinued by a predoctoral student of Dr. Solsona. / L'objectiu d'aquest treball desenvolupat Durant 4 anys ha estat estudiar la Connexina32 (Cx32), sis unitats d'aquest proteína formen un hemicanal anclat a la membrana plasmàtica, dos hemicanals de cèl·lules adjacents formen una unió tipus gap. Mutacions en la Cx32 s'han relacionat amb la forma lligada al cromosoma X de la malaltia de Charcot-Marie-Tooth, una malaltia neurodegenerativa perifèrica. La Cx32 s'expressa en molts teixits però les mutacions només afecten les cèl·lules de Schwann, on la Cx32 s'expressa als paranodes i a les cissures d'Schmidt-Lanterman. Utilitzant oòcits de Xenopus per expressar Cx32, hem mesurat l'alliberació d'ATP i la corrent generada després de sotmetre el oòcits a una despolarització. L'ATP es va detectar utilitzant els enzims luciferina i luciferasa i les corrents utilitzant el sistema de fixació de voltatge amb dos elèctrodes. Després vem estimula electricament nervi ciàtic sencer de rata i ratolí i vem poder captar alliberació d'ATP amb preferència per certes regions diferènciades. Per tal de diferenciar si aquest ATP alliberat provenia de les cèl·lules de Schwann i no dels axons de les neurones també vam estudiar l'alliberació d'ATP en cèl·lules de Schwann en cultiu i el xoc hipotònic també provoca alliberació d'ATP. Vem veure que les cèl·lules de Schwann alliberen ATP però no si ho fan a través de connexines. Primer vem realitzar inmunofuorescències per detectar la presència i posició de les connexines expressades a les cel·lules de Schwann (Cx32, Cx29 i Cx43) i vem trobar presència de Cx32 i Cx29 en les regions paranodals i a les cissures d'Schmidt-Lanterman, i Cx43 al llarg de la veina formada per la cel·lula de Schwann, amb certa preferència per les regions paranodals. Finalment, donada la periodicitat de la Cx32 era un bon candidat per l'alliberació d'ATP a través de les c'el·lules de Schwann que envolten els axons del nervi ciàtic, per veure i la Cx32 alliberava ATP vem Utilitzar cèl·lules HeLa transfectades amb Cx32 i vam capturar l'alliberació d'ATP després d'un xoc hipotònic, també utilitzant la luciferina i la luciferasa, però no vem trobar diferències entre les cèl·lules transfectades amb Cx32 i les que no ho estaven. Així, la Cx32 no allibera ATP en resposta a un estímul hipotònic, però podria en resposta a una depolarització, l'estíml fisiològic que activa l'obertura d'hemicanals de Cx32. Finalment, en experiments de fixació de voltatge expressant la Cx32 amb sintaxina 1A hi havia una inhibició parcial de les corrents d'entrada i de sortia, i de l'ATP alliberat, inhibició que no es va reproduir en els experiments de xoc hipotònic en cèl·lules HeLa transfectades amb Cx32 i sintaxina. Per seguir traballant en la línia de l'estudi de la Cx32 i l'alliberació d'ATP, i la relació que això pot tenir an el desenvolupament de la malaltia de CMT es van triar i generar cinc constructes de Cx32 humana amb mutacions diferents descrites en malalts de CMTX, per tal d'observar l'alliberació d'ATP a través d'hemicanals de Cx32 mutada tant en els experiments de TEVC amb oòctis, com en experiments amb cèl·lules de mamífer transfectades. Aquesta darrera part no va ser acabad però en l'actualitat està esssent realitzada per un altre becari predoctoral del Dr. Solsona.

Hereditary Motor and Sensory Neuropathy-Russe (HMSNR) is a rare recessive form of Charcot-Marie-Tooth disease (CMT) that has been identified in the European Gypsy (Roma) population. Clinically, HMSNR manifests with typical CMT symptoms, while no associated features have been detected. Distinct neuropathological features of HMSNR include the presence of numerous clusters of thinly myelinated fibres originating from regenerative activity. HMSNR has been previously mapped to chromosome 10q using a large Bulgarian Gypsy kindred. Subsequent identification of related chromosome 10q haplotypes in Spanish and Romanian Gypsy families suggested a founder mutation in the Gypsy population as the cause of HMSNR. This thesis describes the refined mapping of the HMSNR gene by generating a high-density physical-genetic map of the HMSNR region containing 20 microsatellite markers and 229 SNPs and insertion/deletions which allowed meticulous mapping of recombination breakpoints resulting in a reduction of the HMSNR gene region from 1 Mb to just 63.8 kb. Analysis of positional candidates by direct sequencing included 14 known genes, 7 predicted genes and 42 expressed sequence tags (ESTs) nonoverlapping with the genes. 78 putative HMSNR mutations were identified, two of which exhibit complete segregation with the HMSNR phenotype. Both are located in the so-called testis-specific part of unexpected candidate gene hexokinase 1 (HK1), in a rare alternative untranslated 5’ exon of HK1 and in the adjacent downstream intron. Expression analysis of transcripts containing the alternative exon suggests that the exon is not confined to testis but may be expressed in the nervous system. It remains to be speculated how a gene that functions in the fundamental process of energy generation might be involved in a neuropathy. Further investigations are likely to expand the knowledge about the importance of HK1 in the peripheral nervous system and may elucidate new roles of HK1

[Truncated abstract] Hereditary Motor and Sensory Neuropathy Lom (HMSNL) is a severe autosomal recessive peripheral neuropathy, the most common form of demyelinating Charcot-Marie-Tooth (CMT) disease in the Roma (Gypsy) population. The mutated gene, N-myc downstream-regulated gene 1 (NDRG1) on chromosome 8q24, is widely expressed and has been implicated in a wide range of processes and pathways. In this study we have aimed to assess the overall contribution of this gene to the pathogenesis of peripheral neuropathies, in cases where the most common causes of CMT disease havebeen excluded, as well as to gain clues about its function through the identification of its interactions with other proteins. Sequence analysis of NDRG1 in 104 patients with CMT disease and of diverse ethnicity identified one novel disease-causing mutation, IVS8-1G>A (g.2290787G>A), which affects the splice-acceptor site of IVS8 and results in the skipping of exon 9 . . . The results suggest a defect in Schwann cell lipid trafficking as a major pathogenetic mechanism in CMT4D. At the same time, database searches showed that the chromosomal location of NDRG1 coincides with a reported High-Density Lipoprotein-Cholesterol Quantitive Trait Locus (HDL-CQTL) in humans and in mice. A putative role of NDRG1 in the general mechanisms of HDL-mediated cholesterol transport was supported by biochemical studies of blood lipids, which revealed an association between the Gypsy founder mutation, R148X, and decreased HDL-C levels. These findings suggest that while peripheral neuropathy is the drastic result of NDRG1 deficiency, the primary role of the protein may be related to general mechanisms of lipid transport⁄metabolism.

Diss. (sammanfattning) Umeå : Umeå universitet, 2009. / Härtill 4 uppsatser.

Diss. (sammanfattning) Umeå : Univ., 2009.

Human histidyl-tRNA synthetase (HARS) is an aminoacyl-tRNA synthetase (AARS) that catalyzes the attachment of the amino acid histidine to histidyl-tRNA (tRNAHis) in a two-step reaction that is essential for protein translation. Currently, two human diseases, Usher Syndrome IIIB (USH3B) and an inherited peripheral neuropathy, Charcot Marie Tooth Syndrome (CMT), have been linked genetically to single point mutations in the HARS gene. The recessive HARS USH3B mutation encodes an Y454S substitution localized at the interface between the anticodon-binding domain and the catalytic domain of the opposing subunit. Patients with Usher Syndrome IIIB lose their sight and hearing during their second decade of life, and clinicians have observed that the onset of deafness and blindness may be episodic and correlate with febrile illness. Furthermore, some young USH3B patients present with a fatal form of acute respiratory distress. In addition to the single HARS mutation linked to Usher Syndrome, eight other mutations in the HARS gene are associated with CMT, an inherited peripheral neuropathy. Peripheral neuropathies are associated with progressive and length-dependent damage of the motor and sensory neurons that transmit information to the spinal cord. The age of onset and phenotypic severity of CMT linked to HARS is highly variable. When expressed in a yeast model system, the HARS variants are dominantly lethal, and confer defects in axonal guidance and locomotor deficiencies when expressed in C.elegans. Here, the biochemical characterization of the HARS USH3B and three peripheral neuropathy variants are described. The approaches included enzyme kinetic analysis with purified HARS enzymes to monitor catalytic deficiencies, differential scanning fluorimetry (DSF) to evaluate structural instability, and cellular models to detect physiological effects of axonal outgrowth by CMT variants. The results suggest that Usher Syndrome IIIB is unlikely to be a consequence of a simple loss of aminoacylation function, while HARS-linked peripheral neuropathy variants all share common catalytic defects in aminoacylation. The HARS system represents a notable example in which two different complex human diseases arise from distinct mutations in the same parent gene. By understanding the biochemical basis of these inherited mutations and their link to Usher Syndrome and CMT, it may be possible to develop mechanism-based therapies to improve the quality of life of patients afflicted with them.