Efecto de la hipotiroxinemia gestacional sobre la integridad de la barrera intestinal de la progenie
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Fecha
2018
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Facultad/escuela
Idioma
es
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Universidad AndrƩs Bello
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Licencia CC
Licencia CC
Resumen
La hipotiroxinemia (HTX) es una condiciĆ³n que se caracteriza por la disminuciĆ³n de los
niveles plasmƔticos de 3,5,3'5'-L-tetra-yodo-tironina (T4) mientras que los niveles
plasmƔticos de 3,4,3'-L-tri-yodo-tironina (T3) y de la hormona estimulante de la tiroides
(TSH) permanecen normales. La HTX gestacional es daƱina en el feto puesto que genera
una impronta irreversible en el feto. Las hormonas tiroideas (HT) tienen un importante rol
en el desarrollo intestinal y en la mantenciĆ³n de la homeostasis intestinal ya que estimulan
la proliferaciĆ³n de cĆ©lulas madres y cĆ©lulas epiteliales del intestino. AdemĆ”s, las HT
participan del recambio de las cƩlulas epiteliales intestinales durante toda la vida. Debido a
que las cƩlulas epiteliales intestinales forman la barrera intestinal, la cual es la encargada de
permitir y bloquear el paso de molƩculas al organismo, es posible que la progenie gestada
en HTX tenga alterada la permeabilidad intestinal. En base a estas evidencias se propone la
siguiente hipĆ³tesis de trabajo: "La hipotiroxinemia gestacional aumenta la permeabilidad
intestinal y la inflamaciĆ³n del intestino de la progenie" Para evaluar esta hipĆ³tesis
propusimos los siguientes objetivos especĆficos: 1) Evaluar la permeabilidad intestinal de
la progenie gestada en hipotiroxinemia; 2) Evaluar la histologĆa intestinal y molĆ©culas
relacionadas con inflamaciĆ³n en el intestino de la progenie gestada en hipotiroxinemia. Para
llevar a cabo estos objetivos se realizaron ensayos de permeabilidad in vivo utilizando FitCdextrano y HRP y ex vivo utilizando FSA y HRP. Los resultados obtenidos mostraron un
aumento significativo de la permeabilidad paracelular a nivel del Ćleon de la progenie gestada
en HTX. El anĆ”lisis histolĆ³gico de cortes de Ćleon teƱidos con hematoxilina y eosina mostrĆ³
mayor infiltrado celular, una mucosa mƔs ensanchada y una submucosa mƔs delgada en la
progenie gestada HTX. Patrones similares a un cuadro de inflamaciĆ³n intestinal. Se observĆ³
aumento en la expresiĆ³n del RNA mensajero para HO1 y disminuciĆ³n para el RNA mensajero de NQO 1. Mientras que no se observaron diferencias significativas para los RNA
mensajeros ni la proteĆna de TNFa, INFy e IL-10. El anĆ”lisis del contenido de proteĆnas que
componen a las uniones estrechas como son ZO-1 y Ocludina mostrĆ³ que el contenido de
ZO-1 en el Ćleon estĆ” disminuido en la progenie gestada en HTX en comparaciĆ³n a la
progenie control. Mientras el contenido de ocludina es similar en ambas progenies. Los
resultados obtenidos en esta tesis apoyan la hipĆ³tesis de que la HTX gestacional imprime en
la progenie mayor permeabilidad en la barrera intestinal del ileĆ³n. AdemĆ”s, los resultados
del anĆ”lisis histolĆ³gico de esta tesis sugieren que el ileum de la progenie gestada en HTX
presenta un estado inflamatorio basal. Este estado inflamatorio y la mayor permeabilidad de
la barrera intestinal del ileum en la progenie gestada en HTX podrĆa ser un factor que
contribuyese al desarrollo de patologĆas como mal de Crohn, enfermedad celiaca o
enfermedades del SNC asociadas a mayor permeabilidad intestinal como Parkinson y
esquizofrenia.
Hypothyroxinemia (HTX) is a condition characterized by plasmatic reduction of 3,5,3'5'-Ltetra-yodo-tironina (T4), meanwhile the levels of 3,4,3'-L-tri-yodo-tironina (T3) and TSH remain normal. Gestational HTX is a harmful condition for the offspring affecting the function of the central nervous system (CNS) and immune system. The mechanism that underlie these effects are unknown. Moreover, thyroid hormones (HT) play important roles at the intestine. It has been shown that HTs participate in the maintenance of intestinal homeostasis, stimulate the proliferation of intestinal stem cells and intestinal epithelial cells, and regulate the turnover of intestinal epithelial cells during the whole life. Intestinal epithelial cells form the intestinal barrier that is responsible for the selective passage of molecules from intestinal lumen to the body. Several reports have shown that the proper function of the intestinal barrier is essential for the function of the CNS and immune system. Thus, it could be possible that the progeny gestated in HTX will have altered the permeability of the intestinal barrier favoring the development of alterations at the CNS and immune system. Based on these evidences, we propose the following hypothesis: "Gestational hypothyroxinemia increases the permeability of the intestinal barrier and the inflammation at the intestine of the offspring". To evaluate this hypothesis the following aims are proposed: 1) To evaluate the intestinal permeability of the progeny gestated in hypothyroxinemia. 2) To determine the histology of the intestine and the molecules related to inflammation in the intestine of the offspring gestated in hypothyroxinemia. For that in vivo permeability assays were performed with FITC-dextran and HRP as markers for paracellular and transcellular permeability respectively. To analyze which intestinal region could have altered its permeability, ex vivo permeability assays were performed with Ussing chambers and FSA and HRP as markers for paracellular and transcellular permeability respectively. A significant increase of the paracellular permeability was detected in the ileum of the offspring gestated in HTX. The histology analysis indicated an increase in the width of the mucosa layer, a reduction in the width of the submucosa layer and an increase of cellular infiltrate at the mucosa layer of the offspring gestated in HTX. These results suggest that the offspring gestated in HTX could have an inflammatory state in the intestine. The relative expression analysis of the transcripts codifying for proteins of the antioxidant machinery showed a significant increase in the relative expression of HO mRNA and a significant decrease of the relative expression of NQO1 mRNA. The intestine content of TNFct, IFNy and IL-10 were similar between the offspring gestated in HTX and control. The content of tight junction proteins as ZO-1 and Occludin in the intestine were analyzed by western blot. No significant differences were observed in the content of Occludin and a significant decrease in the content of ZO-1 was observed in the ileum of the progeny gestated in HTX. In summary, the results of this thesis support the hypothesis that gestational HTX increases the paracellular permeability of the intestinal barrier at ileum. Moreover, the histological analysis of the ileum from the offspring gestated in HTX has an inflammatory basal state. This inflammatory state plus the higher permeability in the ileum in the offspring gestated in HTX could be a factor that could contribute to the development of pathologies like celiac disease, Crohn disease, Parkinson disease or schizophrenia.
Hypothyroxinemia (HTX) is a condition characterized by plasmatic reduction of 3,5,3'5'-Ltetra-yodo-tironina (T4), meanwhile the levels of 3,4,3'-L-tri-yodo-tironina (T3) and TSH remain normal. Gestational HTX is a harmful condition for the offspring affecting the function of the central nervous system (CNS) and immune system. The mechanism that underlie these effects are unknown. Moreover, thyroid hormones (HT) play important roles at the intestine. It has been shown that HTs participate in the maintenance of intestinal homeostasis, stimulate the proliferation of intestinal stem cells and intestinal epithelial cells, and regulate the turnover of intestinal epithelial cells during the whole life. Intestinal epithelial cells form the intestinal barrier that is responsible for the selective passage of molecules from intestinal lumen to the body. Several reports have shown that the proper function of the intestinal barrier is essential for the function of the CNS and immune system. Thus, it could be possible that the progeny gestated in HTX will have altered the permeability of the intestinal barrier favoring the development of alterations at the CNS and immune system. Based on these evidences, we propose the following hypothesis: "Gestational hypothyroxinemia increases the permeability of the intestinal barrier and the inflammation at the intestine of the offspring". To evaluate this hypothesis the following aims are proposed: 1) To evaluate the intestinal permeability of the progeny gestated in hypothyroxinemia. 2) To determine the histology of the intestine and the molecules related to inflammation in the intestine of the offspring gestated in hypothyroxinemia. For that in vivo permeability assays were performed with FITC-dextran and HRP as markers for paracellular and transcellular permeability respectively. To analyze which intestinal region could have altered its permeability, ex vivo permeability assays were performed with Ussing chambers and FSA and HRP as markers for paracellular and transcellular permeability respectively. A significant increase of the paracellular permeability was detected in the ileum of the offspring gestated in HTX. The histology analysis indicated an increase in the width of the mucosa layer, a reduction in the width of the submucosa layer and an increase of cellular infiltrate at the mucosa layer of the offspring gestated in HTX. These results suggest that the offspring gestated in HTX could have an inflammatory state in the intestine. The relative expression analysis of the transcripts codifying for proteins of the antioxidant machinery showed a significant increase in the relative expression of HO mRNA and a significant decrease of the relative expression of NQO1 mRNA. The intestine content of TNFct, IFNy and IL-10 were similar between the offspring gestated in HTX and control. The content of tight junction proteins as ZO-1 and Occludin in the intestine were analyzed by western blot. No significant differences were observed in the content of Occludin and a significant decrease in the content of ZO-1 was observed in the ileum of the progeny gestated in HTX. In summary, the results of this thesis support the hypothesis that gestational HTX increases the paracellular permeability of the intestinal barrier at ileum. Moreover, the histological analysis of the ileum from the offspring gestated in HTX has an inflammatory basal state. This inflammatory state plus the higher permeability in the ileum in the offspring gestated in HTX could be a factor that could contribute to the development of pathologies like celiac disease, Crohn disease, Parkinson disease or schizophrenia.
Notas
Tesis (BioquĆmico, MagĆster en BioquĆmica)
Esta tesis se realizĆ³ en el Laboratorio de BiologĆa Celular y FarmacologĆa de la Facultad de Ciencias de la Vida de la Universidad AndrĆ©s Bello y fue financiada por el proyecto FONDECYT Na 1161525, por el Instituto Milenio de InmunologĆa e Inmunoterapia IMIl P09/16-F y proyecto nĆŗcleo DI-471-15/N.
Esta tesis se realizĆ³ en el Laboratorio de BiologĆa Celular y FarmacologĆa de la Facultad de Ciencias de la Vida de la Universidad AndrĆ©s Bello y fue financiada por el proyecto FONDECYT Na 1161525, por el Instituto Milenio de InmunologĆa e Inmunoterapia IMIl P09/16-F y proyecto nĆŗcleo DI-471-15/N.
Palabras clave
Hipotiroxinemia Gestacional, Hormonas Tiroideas, InflamaciĆ³n (Medicina)