Dietas altas en grasas y sus efectos sobre el intestino / Diets high in fats and their effects on the intestine

El objetivo de esta revisión fue exponer el conocimiento actual sobre la relación existente entre dietas altas en grasa (DAG), alteraciones morfológicas de la mucosa intestinal, efectos inflamatorios y cáncer intestinal. Las DAG inicialmente producen aumento de la microbiota patógena, lo que reduce la cantidad y calidad de la secreción de los exocrinocitos caliciformes, disminuyendo la efectividad de la barrera intestinal. Las bacterias y sus lipopolisacaridos (LPS) promueven la secreción de citoquinas proinflamatorias activando vías de inflamación, que a su vez afectan la integridad de las uniones intercelulares alterando la barrera intestinal. Lo anterior, permite que los LPS ingresen a la lámina propia y circulación sanguínea produciendo inflamación local y sistémica. Así mismo, las DAG generan efectos nocivos en la morfología y función de la mucosa gastrointestinal lo que podría favorecer el desarrollo de cáncer. Lo anterior, podría deberse a que el consumo de DAG es capaz de aumentar la proliferación de células de la mucosa y el número y proliferación de células madres tumorales en el intestino.

The aim of this review was to present current knowledge about the relationship between high fat diets (HFD), morphological alterations of intestinal mucosa, inflammatory effects and intestinal cancer. The HFD initially produces an increase in the pathogenic microbiota, which reduces quantity and quality of secretion of goblet cells, decreasing the effectiveness of intestinal barrier. Bacteria and their lipopolysaccharides (LPS) stimulate the secretion of proinflammatory cytokines by activating inflammation pathways, which in turn affect the integrity of intercellular junctions by changing intestinal barrier. The above allows the LPS enter to lamina propria and blood circulation producing local and systemic inflammation. Likewise, HFD generate deleterious effects on morphology and function of gastrointestinal mucosa, which could favor the development of cancer. This could be due to the fact that consumption of HFD is capable of increasing proliferation of mucosal cells and number and proliferation of tumor stem cells in the intestine.

Tumor necrosis factor alpha increases epithelial barrier permeability by disrupting tight junctions in Caco-2 cells

The objectives of this study were to determine the effect of tumor necrosis factor alpha (TNF-á) on intestinal epithelial cell permeability and the expression of tight junction proteins. Caco-2 cells were plated onto Transwell® microporous filters and treated with TNF-á (10 or 100 ng/mL) for 0, 4, 8, 16, or 24 h. The transepithelial electrical resistance and the mucosal-to-serosal flux rates of the established paracellular marker Lucifer yellow were measured in filter-grown monolayers of Caco-2 intestinal cells. The localization and expression of the tight junction protein occludin were detected by immunofluorescence and Western blot analysis, respectively. SYBR-Green-based real-time PCR was used to measure the expression of occludin mRNA. TNF-á treatment produced concentration- and time-dependent decreases in Caco-2 transepithelial resistance and increases in transepithelial permeability to the paracellular marker Lucifer yellow. Western blot results indicated that TNF-á decreased the expression of phosphorylated occludin in detergent-insoluble fractions but did not affect the expression of non-phosphorylated occludin protein. Real-time RT-PCR data showed that TNF-á did not affect the expression of occludin mRNA. Taken together, our data demonstrate that TNF-á increases Caco-2 monolayer permeability, decreases occludin protein expression and disturbs intercellular junctions.