Caracterização glial e citotoxicidade glutamatérgica no microambiente tumoral e adjacências em modelo de glioma intrínseco difuso de ponte: uma análise pré-clínica
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Tipo
TCC
Data de publicação
2024-12
Periódico
Citações (Scopus)
Autores
Shoji, Leandro Kaoru
Orientador
Assis, Danielle Varin de
Ribeiro, Miriam Oliveira
Ribeiro, Miriam Oliveira
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Resumo
O glioma intrínseco difuso de ponte (GIDP) é um tumor cerebral pediátrico letal e
intratável devido à sua natureza infiltrativa, localização anatômica, e barreira
hematoencefálica bem preservada, sendo ainda um grande desafio clínico. As
células neoplásicas podem recrutar, modular e interagir com células locais, incluindo
as gliais (astrócitos e micróglias) e imunes, constituindo um microambiente tumoral
(MAT) complexo e dinâmico. Os astrócitos são responsáveis pela depuração de
glutamato através do transportador EAAT2, atenuando seus efeitos excitatórios
frente ao seu receptor específico NMDAR. Na vigência da neoplasia, o glutamato
possui papel pró-tumoral, assim, possíveis alterações glutamatérgicas e de
receptores podem estar envolvidos na interação celular no MAT. A micróglia modula
a ação astrocitária, porém, o sistema imune silente da ponte contribui ainda mais
para a progressão tumoral. Portanto, decifrar os mecanismos pelos quais as
interações de astrócitos no MAT influenciam a progressão do DIPG pode ser crucial
para o desenvolvimento de novas terapias. Assim, o objetivo desse trabalho foi
analisar o MAT e adjacências frente a caracterização das células da glia e
citotoxicidade glutamatérgica em modelo experimental de GIDP. Por estereotaxia,
foram injetadas células da linhagem F98 ou salina na região pontina de ratas
Fischer344. O grupo controle não passou por intervenção cirúrgica. No 14º dia pós cirúrgico, os animais foram avaliados no teste do campo aberto e eutanasiados.
Posteriormente, os encéfalos foram submetidos ao ensaio de imunoistoquímica, e
quantificada a imunorreatividade (IR) de Iba-1 (micróglias/macrófagos), GFAP
(astrócitos), EAAT2 e NMDAR nas regiões intra e peritumorais. Foi observado o
aumento da IR de Iba-1, GFAP e EAAT2 nos animais com GIDP comparados aos
controles, e quanto a IR de NMDAR não foram observadas diferenças estatísticas
entre os grupos. A presença de micróglia observada predominantemente na região
intratumoral, sugere um mecanismo de modulação imune induzida pelo tumor. Já
astrócitos e EAAT2 predominantes na região peritumoral, sugerem uma
comunicação glioma-astrócito, questionando sua participação, pois seu aumento tem
sido considerado uma estratégia antitumoral. Já o NMDAR, necessita de
investigação quanto ao seu padrão de ativação. Nossos dados sugerem que as
células da glia e o desbalanço glutamatérgico estão envolvidos com o
desenvolvimento/progressão do GIDP.
Diffuse Intrinsic Pontine Glioma (DIPG) is a lethal and untreatable pediatric brain tumor due to its infiltrative nature, anatomical location, and well-preserved blood brain barrier, posing a significant clinical challenge. Neoplastic cells can recruit, modulate, and interact with local cells, including glial (astrocytes and microglia) and immune cells, creating a complex and dynamic tumor microenvironment (TME). Astrocytes are responsible for glutamate clearance through the EAAT2 transporter, mitigating its excitatory effects on its specific receptor, NMDAR. In the context of neoplasia, glutamate plays a pro-tumoral role, suggesting that potential glutamatergic alterations and receptor changes might be involved in cellular interactions within the TME. Microglia modulate astrocytic actions; however, the immune silence of the pons further contributes to tumor progression. Deciphering the mechanisms by which astrocytic interactions in the TME influence DIPG progression may therefore be crucial for developing new therapies. This study aimed to analyze the TME and adjacent areas by characterizing glial cells and glutamatergic cytotoxicity in an experimental DIPG model. Using stereotaxy, F98 cell lines or saline were injected into the pontine region of Fischer344 rats. The control group underwent no surgical intervention. On the 14th postoperative day, animals were evaluated using the open field test and euthanized. Subsequently, brain tissue was subjected to immunohistochemistry assays, quantifying the immunoreactivity (IR) of Iba-1 (microglia/macrophages), GFAP (astrocytes), EAAT2, and NMDAR in intra- and peritumoral regions. An increase in IR of Iba-1, GFAP, and EAAT2 was observed in DIPG animals compared to controls, while no significant differences in NMDAR IR were detected between groups. The predominant presence of microglia in the intratumoral region suggests an immune modulation mechanism induced by the tumor. Conversely, astrocytes and EAAT2, predominantly located in the peritumoral region, suggest glioma-astrocyte communication, raising questions about their role, as their increase has been considered an antitumoral strategy. NMDAR, however, requires further investigation regarding its activation pattern. Our findings suggest that glial cells and glutamatergic imbalance are involved in DIPG development/progression.
Diffuse Intrinsic Pontine Glioma (DIPG) is a lethal and untreatable pediatric brain tumor due to its infiltrative nature, anatomical location, and well-preserved blood brain barrier, posing a significant clinical challenge. Neoplastic cells can recruit, modulate, and interact with local cells, including glial (astrocytes and microglia) and immune cells, creating a complex and dynamic tumor microenvironment (TME). Astrocytes are responsible for glutamate clearance through the EAAT2 transporter, mitigating its excitatory effects on its specific receptor, NMDAR. In the context of neoplasia, glutamate plays a pro-tumoral role, suggesting that potential glutamatergic alterations and receptor changes might be involved in cellular interactions within the TME. Microglia modulate astrocytic actions; however, the immune silence of the pons further contributes to tumor progression. Deciphering the mechanisms by which astrocytic interactions in the TME influence DIPG progression may therefore be crucial for developing new therapies. This study aimed to analyze the TME and adjacent areas by characterizing glial cells and glutamatergic cytotoxicity in an experimental DIPG model. Using stereotaxy, F98 cell lines or saline were injected into the pontine region of Fischer344 rats. The control group underwent no surgical intervention. On the 14th postoperative day, animals were evaluated using the open field test and euthanized. Subsequently, brain tissue was subjected to immunohistochemistry assays, quantifying the immunoreactivity (IR) of Iba-1 (microglia/macrophages), GFAP (astrocytes), EAAT2, and NMDAR in intra- and peritumoral regions. An increase in IR of Iba-1, GFAP, and EAAT2 was observed in DIPG animals compared to controls, while no significant differences in NMDAR IR were detected between groups. The predominant presence of microglia in the intratumoral region suggests an immune modulation mechanism induced by the tumor. Conversely, astrocytes and EAAT2, predominantly located in the peritumoral region, suggest glioma-astrocyte communication, raising questions about their role, as their increase has been considered an antitumoral strategy. NMDAR, however, requires further investigation regarding its activation pattern. Our findings suggest that glial cells and glutamatergic imbalance are involved in DIPG development/progression.
Descrição
Palavras-chave
glioma intrínseco difuso de ponte , microambiente tumoral , células da glia , citotoxicidade glutamatérgica , diffuse intrinsic pontine glioma , tumor microenviroment , glial cells , glutamatergic citotoxicity