A doença de Chagas é considerada a terceira doença parasitária tropical de maior incidência no mundo, só superada pela malária e esquistossomose, e seu agente causador é o protozoário flagelado Trypanosoma cruzi. O parasita expressa uma enzima de superfície denominada trans-sialidase de Trypanosoma cruzi (TcTS), responsável pela transferência do ácidos siálicos de células do hospedeiro para moléculas de ?-galactose terminais presentes em glicoproteínas de sua superfície. As moléculas de glicoproteína sialiladas estão envolvidas na adesão e subsequente penetração do parasita em células hospedeiras. O papel fundamental da TcTS no reconhecimento e na invasão de células hospedeiras, bem como sua ausência em seres humanos, torna esta enzima um alvo potencial a ser estudado. A TcTS é específica em catalisar, preferencialmente, a transferência de ácido siálico para moléculas de mucina, originando ligações ?-2,3 com unidades de ?-galactose aceptoras na superfície do parasita. Considerando a importância da unidade de galactose e da função carboxila do ácido siálico para interações no sítio ativo de TcTS, priorizamos na síntese de derivados galactosil-triazolo-benzenossulfonamidas com diferentes substituintes, visto que o grupo sulfonamida é bioisóstero do ácido carboxílico, na busca de potenciais inibidores de TcTS. Os derivados galactosiltriazolo- benzenossulfonamidas 45-51 foram preparados via estratégia de click chemistry, por reação de ciclo-adição azido-alcino catalisada por Cu(I) (CuAAC), a partir do intermediário de galactose contento função amino terminal 30 e os derivados aril azidas 38-44. Após etapa de desacetilação, os produtos obtidos 52-58 foram testado em TcTS por ensaio fluorimétrico in vitro para avaliação de sua atividade inibitória. Os resultados obtidos são interessantes e bastante promissores, principalmente com os obtidos com o produto 58 (contendo o grupo galactosiltriazólico ligado a sulfapiridina), que apresentou atividade inibitória promissora (81%) na concentração de 1,0 mM, abrindo perspectivas para a síntese de um maior número de derivados galactosil-triazolo-benzenossulfonamidas com diferentes substituintes em R, para o estabelecimento de estudos de relação estruturaatividade. Adicionalmente, os compostos 53-55 foram testados em ensaios in vitro para avaliação de sua atividade tripanocida e citotóxica, e apresentaram atividade tripanocida máxima de 50%, normalmente nas concentrações de 500 a 250 ?M, com destaque para o derivado 55, contendo o grupo galactosil-triazólico ligado a sulfamerazina, que apresentou atividade moderada, mas superior ao benznidazol nas concentrações mais baixas (15,0 - 1,9 ?mol.L-1). Por outro lado, de acordo com os resultados do ensaio de citotoxicidade, a atividade citotóxica foi observada apenas nas concentrações mais elevadas, similar ao benznidazol. / Chagas disease is considered the third most common tropical parasitic disease worldwide, after malaria and schistosomiasis, and its causer is the flagellate protozoan, Trypanosoma cruzi. The parasite expresses a surface enzyme known as Trypanosoma cruzi trans-sialidase (TcTS), responsible for the transference of sialic acid from host cell to ?-galactose terminal molecules present in surface glycoproteins. Sialylated glycoproteins molecules are involved in adhesion and further penetration of parasite in host cell. Due to TcTS primordial role in recognizing and invasion of host cells, as well as its absence in humans, this enzyme becomes a potential target to be investigated. TcTS is specific on catalyzing, specially, transference of sialic acid to mucin molecule giving ?-2,3 bond with ?-galactose moiety in parasite surface. Considering the importance of the galactose moiety and the function of carboxylic in sialic acid for interactions in TcTS enzyme, we prioritized the synthesis of galactosyl-triazol-benzenesulfonamides derivatives with different substituents since sulfonamide group is bioisoster of carboxylic acid, in attempt to produce potential inhibitors of TcTS. The galactosyl-triazol-benzenesulfonamides derivatives 45-51 were prepared via click chemistry reaction (Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC)) from galactose intermediate with terminal amino group 30 and aril azides derivatives 38-44. After removing acetyl group, the inhibiting activity of products 52-58 were evaluated in TcTS fluorimetric in vitro assay. We found very promising results, specially with 58 (containing galactosyl-triazolic group bonded to sulfapyridine), wich showed 81% of inhibitory activity in 1,0mM solution, bringing expectations for synthesis of greater number of galactosyl-triazolbenzenesulfonamides derivatives with different substituents in R, to establish studies of structure relationship activity. Additionally, trypanocidal and cytotoxic activity of compounds 53-55 were tested and showed maximum activity of 50%, commonly in concentrations of 500 to 250 ?M, specially compound 55, containing galactosyltriazolic group bonded to sulfamerazine, with showed moderate activity, but higher then benznidazol in lower concentrations (15,0 - 1,9 ?mol.L-1). On the other hand, according to cytotoxicity results, activity were observed only in higher concentrations, as for benznidazol.

A neuraminidase-1 (Neu1) participa da regulação do catabolismo de sialoglicoconjugados nos lisossomos. A deficiência congênita da Neu1 é a base da sialidose, doença neurossomática grave associada a deformidades osteoesqueléticas, hipotonia e fraqueza muscular. Camundongos com deficiência de Neu1 (Neu1-/-) desenvolvem uma forma atípica de degeneração muscular caracterizada por expansão da matriz extracelular (MEC), invasão das fibras musculares por fibroblastos, fragmentação do citoplasma, formação vacuolar e atrofia muscular. Apesar de a degeneração muscular estar bem caracterizada nestes animais, a miogênese ainda não havia sido estudada. O objetivo desta pesquisa foi avaliar o envolvimento da Neu1 no processo de regeneração muscular, após aplicação de cardiotoxina (CTX) em camundongos Neu1-/-, em comparação com controles normais. A CTX foi administrada no músculo tibial anterior direito e os animais foram eutanasiados por deslocamento cervical 1, 3, 5, 7, 10, 14, 21 e 28 dias após a lesão. Os músculos foram analisados através de histologia; medição da área transversa das fibras musculares centronucleadas; verificação do potencial proliferativo celular por quantificação de marcação de BrdU; imunoistoquímica para inflamação, fibras regenerativas e fibrose; e expressão gênica e proteica de fatores de transcrição musculares. Os dados foram comparados estatisticamente e as variações significativas devem apresentar p <= 0,05. Nos animais com deficiência de Neu1, o processo inflamatório (especialmente a reação macrofágica) e o potencial proliferativo estavam aumentados nas fases iniciais, acompanhados da hiperexpressão de Pax7. Observamos atraso na maturação muscular caracterizado por maior expressão de miosina embrionária em estágios mais tardios da regeneração. Os genes MyoD e MyoG estavam com expressão aumentada no período de 5 a 10 dia após a lesão, embora a expressão destas proteínas estivesse reduzida. Ao final da regeneração, houve maior deposição de reticulina na MEC, indicando processo fibrótico. A Neu1 parece atuar em todos os estágios da regeneração muscular, desde a fase aguda da lesão através do controle da proliferação celular, até a maturação muscular e estágios finais em que regularia a deposição de componentes da MEC / Neuraminidase-1 (Neu1) participates in sialoglycoconjugates catabolism in lysosomes. Congenital Neu1 deficiency is the basis of sialidosis, a severe neurosomatic disorder associated with osteoskeletal deformities, hypotonia and muscle weakness. Mice with Neu1 deficiency (Neu1-/-) develop an atypical form of muscle degeneration characterized by abnormal fibroblast proliferation and expanded extracellular matrix (ECM), invasion of muscle fibers by fibroblast, cytosolic fragmentation, vacuolar formation and muscle atrophy. Despite muscle degeneration is well characterized in these animals, myogenesis has not been studied so far. The aim of this study was to evaluate the involvement of Neu1 in muscle regeneration process after cardiotoxin (CTX) injection in Neu1-/- mice and normal controls. CTX was applied in the right tibialis anterior muscle, and the animals were euthanized by cervical dislocation 1, 3, 5, 7, 10, 14, 21 and 28 days after injury. The muscles were analyzed through histology; cross-sectional area of regenerative muscle fibers; quantification of BrdU labeling; immunohistochemistry labelling for inflammation, regenerative fibers, and fibrosis; and gene and protein expression of muscle transcription factors. The data were compared and variances considered statistically significant in case p <= 0.05. In animals with Neu1 deficiency, both inflammatory process (mainly macrophagic response) and proliferative potential were increased in the initial stages, accompanied by overexpression of Pax7. We observed delay in muscle maturation characterized by higher expression of embryonic myosin later in muscle regeneration. MyoD and MyoG genes were overexpressed from 5 to 10 days after injury, though the expression of these proteins was reduced. At the end of muscle regeneration, reticulin deposition in ECM was increased, indicating fibrotic process. Neu1 seems to participate in all stages of muscle regeneration, since acute injury phase through the control of cell proliferation, towards muscle maturation, and at the final stages when it would regulate the deposition of ECM components

A doença de Chagas, causada pelo parasita protozoário Trypanosoma cruzi, afeta milhões de pessoas, a maioria delas vivendo na América latina. Apesar dos avanços da medicina e da biotecnologia, ainda existem poucas opções de tratamento para indivíduos com a doença. Assim, é importante compreendermos os detalhes moleculares da infecção parasitária, para que novas alternativas terapêuticas e de diagnóstico possam ser desenvolvidas para esses pacientes. Neste trabalho estudamos esta doença em duas frentes, uma do ponto de vista do parasita, e a outra, da resposta do hospedeiro. Utilizando bioinformática, identifcamos um peptídeo conservado (denominado TS9) presente nas proteínas de superfície gp85/transsialidases do parasita. Este peptídeo é capaz de promover adesão celular e, na sua forma sintética, inibe a entrada do T. cruzi na célula hospedeira. Análise da estrutura proteica revelou que o peptídeo TS9 encontra-se num domínio do tipo laminina-G, lado-a-lado com o peptídeo FLY, outro peptídeo conservado desta grande família, previamente descrito pelo nosso grupo. Juntos, eles formam um sítio de adesão a citoqueratinas e proteínas de flamento intermediário. Na segunda parte, investigamos os antígenos e epítopos reconhecidos pelas imunoglobulinas de pacientes portadores da doença nas suas diferentes formas clínicas: assintomática e cardiomiopatias, leve ou grave. Criamos uma biblioteca de phage display contendo, virtualmente, todos os fragmentos proteicos existentes no T. cruzi, que foi varrida contra imunoglobulinas para a construção de um mapa da resposta humoral dos pacientes com a doença de Chagas. Nossos resultados mostram que a resposta dos pacientes é complexa, e mais de dois mil epítopos foram mapeados. Muitos deles, como os antígenos B13, SAPA e FRA já foram previamente descritos, validando nosso método. Porém, um grande número de novos epítopos, inclusive contra proteína descritas como hipotéticas ou sem função conhecida, também foram encontrados. Seus papéis na infecção e resposta imune da doença merecem, portanto, atenção. Em resumo, as abordagens e técnicas utilizadas nesta tese são inovadoras, e permitiram a identifcação de peptídeos e moléculas que poderão ser úteis para o desenvolvimento de novos métodos diagnósticos e terapêuticos para a doença de Chagas. / Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, afects millions of people, most of them living in Latin America. Despite advances in medicine and biotechnology, there are still few treatment options for individuals with the disease. Thus, it is important to understand the molecular details of the parasitic infection, so that new therapeutic and diagnostic alternatives can be developed for these patients. In this work, we study this disease in two fronts, one from the point of view of the parasite, and the other, of the response of the host. Using bioinformatics, we identifed a conserved peptide (called TS9) present in the surface proteins gp85 / trans-sialidases of the parasite. This peptide is capable of promoting cell adhesion and, in its synthetic form, inhibits the entry of T. cruzi into the host cell. Analysis of the protein structure revealed that the TS9 peptide is in a laminin-G-like domain, side-by-side with the peptide FLY, another conserved peptide of this large family, previously described by our group. Together, they form an adhesion site to cytokeratins and intermediate flament proteins. In the second part, we investigated the antigens and epitopes recognized by the immunoglobulins of patients with the disease in their diferent clinical forms: asymptomatic and cardiomyopathies, mild or severe. We created a phage display library containing virtually all existing protein fragments in T. cruzi. This library was screened against immunoglobulins for the construction of a humoral response map of patients with Chagas disease. Our results show that the response of the patients is complex, and more than 2,000 epitopes have been mapped. Many of them, such as the B13, SAPA and FRA antigens have been previously described, validating our method. However, a large number of new epitopes, including many against proteins described as hypothetical or with no known function, were also found. Their roles in infection and immune response of the disease deserve, therefore, attention. In summary, the approaches and techniques used in this thesis are innovative and have allowed the identifcation of new peptides and molecules that may be useful for the development of new diagnostic and therapeutic methods for Chagas disease.

No description available.

<p>GM2 gangliosidoses encompass a group of chronic neurodegenerative disorders characterized by metabolic defects in ganglioside catabolism and marked intralysosomal accumulation of GM2 in central nervous system (CNS)-resident neurons. Included in this group are Tay-Sachs and Sandhoff disease. Human cases of Tay-Sachs and Sandhoff disease present with devastating neurological deterioration; however, murine models display drastically divergent phenotypes. Tay-Sachs mice avoid pathology via a sialidase-mediated bypass of β-hexosaminidase A (HEXA) deficiency, though the precise mechanism of avoidance is not fully elucidated. The following work aimed to: i) determine if the murine sialidase-mediated bypass could be potentiated in human cells, and ii) help clarify the mechanism of disease avoidance in Tay-Sachs animals.</p> <p>Adenoviral overexpression of truncated CCAAT displacement protein (CDP^831-1505) in human Tay-Sachs neuroglia augmented neuraminidase 1/lysosomal sialidase (NEU1) protein levels, which reduced intralysosomal GM2 accumulations. Chromatin immunoprecipitation revealed binding of CDP^831-1505 to the human <em>NEU1</em> promoter in Tay-Sachs neuroglia. These results provide mechanistic and functional evidence supporting therapeutic exploitation of <em>NEU1</em> for Tay-Sachs disease.</p> <p>Comparison of immunological responses of bone marrow-derived macrophages (BMDMs) to pathogen associated molecular patterns (PAMPs) or GM2 demonstrated that Sandhoff macrophages secrete increased TNF and reduced IL-10 following lipopolysaccharide stimulation. GM2 treatment failed to stimulate an immune response. Such behaviour occurred in the absence of clearly observable intralysosomal ganglioside accumulations. Altered LAMP2 protein size, potentially due to aberrant glycosylation, is hypothesized to disrupt autophagosomal/lysosomal fusion. Subsequent autophagosomal accumulation could result in inherent macrophage hypersensitivity and immunologic irritability. Downstream interleukin-10 (IL-10)/signal transducer and activator of transcription 3 (Stat3) axis, mitogen activated protein kinase (MAPK), and glycogen synthase kinase 3-beta (GSK3β) signaling pathways were affected in Sandhoff BMDMs. These data indicate inherent differences in immunological responses of BMDMs from Sandhoff mice, presumably related to their β-hexosaminidase B (HEXB) deficiency.</p> <p>Data presented here provides evidence to suggest a paradigm shift in the neurodegenerative model of Tay-Sachs and Sandhoff Diseases towards one that places immune cells as an initiating factor for widespread neuroinflammation.</p> / Master of Science (MSc)

Clostridium perfringens is the causative agent of gas gangrene. A lethal infection in mice requires a large inoculum suggesting that the immune system is involved in inhibiting disease. Human monocytic cells and neutrophils killed C. perfringens in vitro when complement was present. Macrophages and neutrophils co-localized with C. perfringens in vivo when bacterial numbers were low. Depletion of neutrophils and monocytes in mice revealed that monocytic cells play a role in inhibiting C. perfringens gas gangrene in mice infected with an intermediate dose. C. perfringens can persist in the tissues and this could be mediated by persistence within macrophages. To examine if the toxin perfringolysin O (PFO) could mediate this, less active variants of PFO were used to examine what occurs between phagosomal escape and cell lysis. The mutant forms of PFO did mediate phagosomal escape in macrophages and were found within macrophages at higher numbers than wild-type C. perfringens. Our data were preliminary but may indicate that less active PFO mediates intracellular persistence. To investigate the role of sialidase in C. perfringens gas gangrene we made nanI-, nanJ-, and nanI-/nanJ- mutants. We observed that NanI is responsible for the majority of sialidase activity of C. perfringens strain 13, that NanJ is an extracellular sialidase, and that these genes are transcriptionally regulated by sialic acid. Murine infection trials revealed that these sialidases may be protective for mice during infection. In conclusion, murine monocytes inhibit disease onset and C. perfringens sialidase enhances mouse survival. However, the toxin PFO if less active promotes the survival of C. perfringens with macrophages. / Master of Science

La trypanosomose est la maladie parasitaire la plus dévastatrice en Afrique, et affecte à la fois les hommes et le bétail. Vu l’inefficacité des stratégies de contrôle actuelles, une stratégie alternative dite “anti-maladie” a été proposée dans le cadre de la trypanosomose animale. Elle vise à neutraliser les effets de la maladie plutôt qu’à éliminer le parasite. Une telle stratégie nécessite une meilleure compréhension du développement de la pathologie ainsi qu’une caractérisation détaillée des facteurs de virulence impliqués. Dans ce contexte, nous nous sommes intéressés à l’étude de l’interaction hôte/pathogène entre les trypanosomes Africains et l’endothélium de l’hôte mammifère. En comparant quatre espèces différentes de trypanosomes Africains, nous avons montré que leurs capacités d’activation des cellules endothéliales étaient distinctes. Nous avons clairement démontré que T. congolense, T. vivax et T. b. gambiense activent les cellules endothéliales via la voie de NF-ƘB, alors que T. b. brucei est incapable d’activer cette voie. Cette activation a induit une résponse pro-inflammatoire in vitro et in vivo, ce qui souligne l’importance de ce mécanisme dans le développement de la maladie. Pour la première fois, nous avons identifié une activité sialidase chez le parasite de l’homme T. brucei gambiense, et nous avons démontré que les trans-sialidases trypanosomales sont les médiateurs de cette activation endothéliale et de la réponse inflammatoire consécutive, et ceci à la fois chez les trypanosomes africains d’homme et d’animaux. De plus, nous avons montré que l’activation endothéliale implique l’activité lectin-like des trans-sialidases et non pas l’activité catalytique, ainsi que des récepteurs sialylés sur la surface endothéliale. En conclusion, ce travail a apporté des avancées considérables dans la compréhension de la relation hôte/pathogène et a permis de désigner les sialidases comme un facteur de virulence central dans le dialogue intermoléculaire durant les trypanosomoses, en faisant une cible de choix pour le vaccin « anti-maladie ». / Trypanosomiasis remains by far the most devastating parasitic disease in Africa affecting both humans and livestock. The current control strategies being not efficient, an alternative “anti-disease” strategy aiming to neutralize the pathological effects of the parasite rather than to eliminate it, was proposed. Therefore, it is essential to understand the development of pathogenesis and characterize the involved pathogenic factors. In this context, we wanted to elucidate the host-pathogen interaction between the African trypanosomes and the mammalian host endothelium. By comparing four different trypanosomes species, we showed that they displayed distinct capacities for activation of endothelial cells. We clearly demonstrated that T. congolense, T. vivax and T. b. gambiense activate the endothelial cells via the NF-ƘB pathway, but not T. b. brucei. This activation caused a pro-inflammatory response in vitro and in vivo, showing the importance of this mechanism in the development of pathogenesis. For the first time, we identified sialidase activity in the human parasite T. brucei gambiense, and demonstrated that the trypanosomal trans-sialidases are the mediators of this endothelial activation and its consequent inflammatory response, for both human and animal trypanosomes. Additionnally, we showed that endothelial cell activation is mediated by the lectin-like domain of the trans-sialidase rather than the catalytic site, and involves sialylated receptors of the endothelial cell surface. In conclusion, our study brings considerable insights into the host-pathogen relationship and designates sialidases as a central virulence factor in the molecular crosstalk during trypanosomiasis, which makes it a perfect target for the anti-disease strategy.

L'utilisation thérapeutique de glycoprotéines recombinantes produites dans le système baculovirus-cellules d'insectes reste limitée par le potentiel de glycosylation de ces cellules, qui produisent essentiellement des structures O- et N-glycanniques courtes. Notre travail s'inscrit donc dans un effort global d'"humanisation" de la glycosylation des protéines produites dans les cellules de Lépidoptères.<br />Nous nous sommes d'abord attachés à comprendre la voie de maturation des N-glycannes dans des cellules Sf9. L'utilisation d'inhibiteurs de la maturation ou du trafic intracellulaire nous a permis d'identifier des intermédiaires clés et de confirmer l'hypothèse que la maturation des N-glycannes dans les cellules d'insectes et de mammifères suivent un chemin métabolique parallèle jusqu'à la formation de l'espèce GlcNAcMan3[Fuc]GlcNAc2. Chez les insectes, cette structure est ensuite substrat d'une β-N-acétylglucosaminidase qui produit l'espèce finale Man3[Fuc]GlcNAc2.<br />Cette voie de maturation peut néanmoins être déviée vers la synthèse de N-glycannes de type complexe par l'addition de glycosyltransférases absentes : ainsi, l'expression d'une β1,4-galactosyltransférase permet la synthèse de l'espèce GalGlcNAcMan3[Fuc]GlcNAc2.<br />Notre intérêt s'est ensuite porté sur l'ingénierie de la sialylation dans les cellules d'insectes, compliquée par l'absence du donneur d'acides sialiques, le CMP-Neu5Ac. Notre stratégie a été d'exprimer la trans-sialidase de Trypanosoma cruzi sur la membrane plasmique des cellules, afin qu'elle puisse sialyler les glycoprotéines sécrétées en utilisant des donneurs du milieu. La construction exprimée grâce à un vecteur baculovirus code une enzyme active, dont une partie est retrouvée sur la membrane plasmique et sur l'enveloppe des particules virales, tandis qu'une partie, croissante avec l'infection, est soluble. Néanmoins, le système permet une sialylation quantitative d'accepteurs exogènes.<br />Notre étude contribue à montrer que l'ingénierie de la glycosylation dans le système baculovirus-cellules d'insectes est envisageable. Pour résoudre le problème de la sialylation, la trans-sialidase est une alternative possible aux sialyltransférases.

Thymoquinone (TQ), a volatile oil component of black seed oil (derived from Nigella sativa), has been shown to have various biological effects including disease treatment and prevention. TQ is believed to share similar properties to the benzoquinones already in use as therapeutic drugs. Based on previous reports on the anti-inflammatory properties of black seed oil and TQ, it was originally hypothesized that TQ would inhibit lipopolysaccharide (LPS)-induced cellular sialidase activity in an anti-inflammatory manner. Sialidase activity was tested on live mouse bone marrow derived primary macrophage cells, BMC-2 macrophage cells, human embryonic kidney epithelial (HEK293) cells and human fibroblast cells using an assay that measures the cleavage of the sialidase specific fluorescent substrate 2’-(4-methylumbelliferyl)-α-DN-acetylneuraminic acid (4-MUNANA). The cleavage of 4-MUNANA causes the release of free 4-methylumbelliferone, which fluoresces at 450nm (blue) after excitation at 365nm. Unexpectedly, TQ induced sialidase activation in all three cell lines and wild type primary macrophage cells. TQ was unable to induce sialidase activity in primary macrophage cells isolated from Neu4 knockout mice suggesting that the TQ activates Neu4 sialidase enzyme. TQ-induced sialidase activity in these live cells was found to occur through intermediate GPCR-associated guanine nucleotide Gαi subunit and matrix metalloproteinase 9 (MMP9) by using specific inhibitors. In addition, TQ was found to induce sialidase activity in Toll-like receptor-deficient HEK293 cells. These latter data suggested that TQ may be activating GPCR Gαi and MMP9 signaling associated with Neu4 sialidase independent of TLRs. It is proposed that TQ-induced sialidase activity may activate Toll-like receptors in macrophage cells and the subsequent production of pro-inflammatory cytokines in the absence of LPS. Immunocytochemical staining of BMC-2 cells shows that TQ induced NFκB activation. NFκB activation was confirmed with electrophoretic mobility shift assay (EMSA) and western immunoblotting techniques. Cytokine arrays were used to test the pro-inflammatory cytokine response induced in mice by 5 hour treatment of TQ, compared to LPS. Mice treated with TQ exhibited an increase in IL-1β, IL-6 and TNF-α production, similar to LPS treatment. Taken together, the findings in these studies suggest that TQ is a novel ligand for Neu4 sialidase activation which consequently induces pro-inflammatory cytokine responses. / Thesis (Master, Microbiology & Immunology) -- Queen's University, 2009-04-21 17:38:10.413

INTRODUÇÃO:A neuraminidase 1 (chamada a seguir por Neu1) regula o catabolismo de sialoglicoconjugados nos lisossomos. A deficiência congênita da Neu1 é a base da sialidose, doença neurossomática grave associada a deformidades osteoesqueléticas, hipotonia e fraqueza muscular. Camundongos com deficiência de Neu1 desenvolvem uma forma atípica de degeneração muscular caracterizada porproliferação anormal de fibroblastoslevando a invasão nas fibras musculares, expansão da matriz extracelular (MEC), fragmentação do citoplasma, formação vacuolar e atrofia muscular. A ocorrência de atrofia muscular indica que a deficiência da Neu1 podeestar relacionada com o controle da massa muscular, a qual é dependente do equilíbrio entre síntese e degradação proteica.Uma característica principalnaMacroautofagia (denominada a seguir por autofagia) é a principal via de degradação intracelular sendo expressamente essencial para a homeostase celular e remoção de materiais citoplasmáticos. Objetivos: Avaliarseos efeitos da deficiência da Neuraminidase 1 afetama indução de autofagia e a formação de autofagossomos e determinar os efeitos do bloqueio da função lisossomal sobre o fenótipo muscular na deficiência da Neuraminidase1.Metodologia:Camundongos Neu1+/-foram cruzados e os filhotes genotipados, onde camundongos Neu1-/-(nocaute) e Neu1+/+(normal),foram utilizados no estudon total=90, sendo 10 em padronizações, 20 para coleta de fibroblastos e 60 para procedimentos in vivo, os grupos experimentais foram divididos em privação alimentar por 2 dias que, por meio da inibição do mTOR, induz a autofagia;grupo detratamento com Colchicina por 4 dias onde irá impedir a junção autofagossomo/lisossomonão havendo a degradaçãolisossomaleadicionado nos dois últimos dias de privação alimentar e o grupo de tratamento comRapamicina por 7 dias, droga com função de inibir seletivamente o mTOR.Após os tratamentos, os animais foram eutanasiadospara coleta dos músculos gastrocnêmios e tibiais anterior. Os músculos foram analisados apósas coloraçõeshistológicas porHematoxilina & Eosina e Fosfatase Ácida; Imunofluorescência de LC3-I/II; Western Blottingdas proteínas LC3-I/II, Lamp-1 e p62/SQSTM e a análise Ultra-estrutural. Além disso, foi realizada cultura de fibroblastos, os quais foram submetidos à privação de nutrientes e ao tratamento com Rapamicina, seguidos dasmesmas metodologias de análise invivo. Resultados:As análises histológicas através de H&E e Fosfatase Ácida não revelaram alterações consistentes na musculatura esquelética de animais submetidos aos tratamentos, mostrando em animais com deficiência de Neu1 um aumento anormal do espaço endomisial, e aumento da atividade lisossomalintracitoplasmáticos. Na análise ultra-estruturalobservou-se em todos os grupos, a presença de diversas estruturas com aspecto autofágico, de diferentes tamanhos, formas e constituintes. Naanálise da expressão do LC3 através de Western Blottingmostrou importante ativação do LC3-II na privação alimentar (com e sem administração de Colchicina) tanto em animais controles quanto em animais com deficiência de Neu1 e uma importante ativação do LC3-I em Rapamicina em ambos os grupos mostrando assim que houve um aumento da via da autofagia através do bloqueio do mTOR. Já na análise de Imunofluorescência não foi possível observar diferença consistenteentre os grupos.A análise in vitrode Western Blottingmostrou que tal ativação foi similar entre fibroblastos Neu1+/+e Neu1-/-. Conclusão:Os experimentos relacionados com a ativação ou inibição da autofagia, não resultaram em diferenças consideráveis entre músculos normais e músculos com deficiência de Neu1. Desta forma, podemos concluir com estes experimentos que aparentemente a Neu1, apesar de ser uma importante enzima lisossomal, não interfere com o processo de autofagia / Introduction:Neuraminidase 1 (hereinafter Neu1) regulates the catabolism of sialoglycoconjugates in lysosomes. The congenital deficiency of Neu1 is the basis of sialidosis, a severe neurosomatic disease associated with osteo-skeletal deformities, hypotonia, and muscle weakness. Mice with Neu1deficient develop an atypical form of muscle degeneration characterized by abnormal fibroblast proliferation leading to muscle fiber invasion, extracellular matrix expansion (ECM), cytoplasm fragmentation, vacuolar formation, and muscle atrophy. The occurrence of muscle atrophy indicates that deficiencyofNeu1 may be related to the control of muscle mass, which is dependent on the balance between synthesis and protein degradation. A major feature in Macroautophagy (hereinafter referred to as autophagy) is the main pathway of intracellular degradation being expressly essential for cellular homeostasis and removal of cytoplasmic materials. Objectives:To evaluate whether the effects of neuraminidase 1 deficiency affect autophagy induction and autophagosome formation and to determine the effects of lysosomal function block on muscle phenotype in neuraminidase 1 deficiency. Methodos:Mice Neu1+/-were crossbred and the genotyped pups, where mice Neu1-/-(knockout) and Neu1+/+(normal), were used in the study ntotal = 90, 10 for standardization, 20 for fibroblast collection and 60 for in vivo procedures, experimental groups were divided into food deprivation for 2 days that, through mTOR inhibition, induces autophagy; Colchicine treatment group for 4 days whereit will prevent autophagosome/lysosome junction without lysosomal degradation and added in the last two days of food deprivation and Rapamycin treatment group for 7 days, drug with function to selectively inhibit mTOR. After the treatments, the animals were euthanized to collect the anterior gastrocnemius and tibial muscles. The muscles were analyzed after histological staining by Hematoxylin & Eosin and Acid Phosphatase; LC3-I/II immunofluorescence; Western Blottingof LC3-I/II, Lamp-1 and p62/SQSTM proteins and Ultra-structural analysis. In addition, fibroblasts were cultured and subjected to nutrient deprivation and Rapamycin treatment, followed by the same in vivo analysis methodologies. Results:Histological analyzes by H&E and Acid Phosphatase did notreveal consistent changes in skeletal muscle of animals submitted to treatments, showing in animals with Neu1 deficiency an abnormal increase in endomysial space and increased intracytoplasmic lysosomal activity.In ultrastructural analysis, it was observed in all groups, the presence of several structures with autophagic aspect, of different sizes, shapes and constituents. The analysis of LC3 expression by Western Blottingshowed important activation of LC3-II in food deprivation (with and without Colchicine administration) in both control and Neu1 deficient animals and an important activation of LC3-I in Rapamycininboth groups,thus showing an increase in the autophagy pathway through mTOR blockade. In the immunofluorescence analysis, it was not possible to observe consistent difference between the groups. In vitro Western Blottinganalysis showed that such activation was similar between Neu1+/+and Neu1-/-fibroblasts. Conclusion: Experiments related to activation or inhibition of autophagy did not result in considerable differencesbetween normal muscles and Neu1 deficient muscles. Thus, we can conclude from these experiments that apparently Neu1, despite being an important lysosomal enzyme, does not interfere with the autophagy process