Células linfoides innatas y células T natural killer en el sistema inmune del tracto gastrointestinal / Innate lymphoid cells and natural killer T cells in the gastrointestinal tract immune system

El tracto gastrointestinal está equipado con un sistema inmune intrínseco altamente especializado. Sin embargo, el intestino soporta una gran carga antigénica que requiere de una respuesta rápida e inespecífica, denominada inmunidad innata, para mantener la homeostasis y proteger al organismo de la entrada de patógenos. En la última década, numerosos estudios han contribuido a desentrañar los requisitos particulares de desarrollo y las funciones específicas de las células que intervienen en la inmunidad innata. En esta revisión, nos centraremos en las células linfoides innatas, un nuevo y heterogéneo grupo de células derivadas de una población linfoide progenitora Id2- dependiente. Estas células han sido categorizadas en base al patrón de citocinas que producen y los factores de transcripción que regulan su desarrollo y funciones. Las células linfoides innatas intervienen en la respuesta temprana contra agentes patógenos, la contención anatómica de la flora comensal, y el mantenimiento de la integridad epitelial. Dentro de las distintas células linfoides innatas haremos especial hincapié en una subpoblación con diversas particularidades, las células T natural killer, un subtipo de linfocitos T que expresan receptores de células T y NK. La fracción más numerosa de células NKT son las denominadas NKT invariantes o iNKT. Las células iNKT, poseen un TCR invariante y reconocen estructuras glicolípidicas presentadas por la molécula CD1d, homóloga de MHC de clase I. Tras su activación, adquieren rápidamente actividad citotóxica y producen citocinas tanto Th1 como Th2, e incluso IL-17. Aunque su papel concreto no está determinado, las células iNKT intervienen en una gran variedad de respuestas inmunes intestinales, desde la tolerancia oral hasta su implicación en diversas patologías del tracto gastrointestinal (AU)

The gastrointestinal tract is equipped with a highly specialized intrinsic immune system. However, the intestine is exposed to a high antigenic burden that requires a fast, nonspecific response -so-called innate immunity- to maintain homeostasis and protect the body from incoming pathogens. In the last decade multiple studies helped to unravel the particular developmental requirements and specific functions of the cells that play a role in innate immunity. In this review we shall focus on innate lymphoid cells, a newly discovered, heterogeneous set of cells that derive from an Id2-dependent lymphoid progenitor cell population. These cells have been categorized on the basis of the pattern of cytokines that they secrete, and the transcription factors that regulate their development and functions. Innate lymphoid cells play a role in the early response to pathogens, the anatomical contention of the commensal flora, and the maintenance of epithelial integrity. Amongst the various innate lymphoid cells we shall lay emphasis on a subpopulation with several peculiarities, namely that of natural killer T cells, a subset of T lymphocytes that express both T-cell and NK-cell receptors. The most numerous fraction of the NKT population are the so-called invariant NKT or iNKT cells. These iNKT cells have an invariant TCR and recognize the glycolipidic structures presented by the CD1d molecule, a homolog of class-I MHC molecules. Following activation they rapidly acquire cytotoxic activity and secrete both Th1 and Th2 cytokines, including IL-17. While their specific role is not yet established, iNKT cells take part in a great variety of intestinal immune responses ranging from oral tolerance to involvement in a number of gastrointestinal conditions (AU)

Nutrient regulation of enteroendocrine cellular activity linked to cholecystokinin gene expression and secretion

No disponible

The hormone cholecystokinin is produced by the enteroendocrine I cells in the intestine, and it plays an important role in a number of physiological processes including digestion and food intake. Recent data suggest that cholecystokinin gene expression and protein secretion are regulated bymacronutrients. The mechanism involves a change in intracellular levels of cAMP and Ca+2, brought about by the activity of a number of nutrient-responsive G protein-coupled receptors, nutrient transporters, ion channels and intracellular enzymes. How these intracellular responses could lead to gene expression and protein secretion are discussed along with new directions for future investigation (AU)

Nutrient sensing in the gastrointestinal tract: Possible role for nutrient transporters

Although it is well established that the presence of nutrients in the gut lumen canbring about changes in GI function, the mechanisms and pathways by which thesechanges occur has not been fully elucidated. It has been known for many years thatluminal nutrients stimulate the release of hormones and regulatory peptides from gutendocrine cells and that luminal nutrients activate intrinsic and extrinsic neural pathwaysinnervating the gut. Activation of gut endocrine cells and neural pathways bynutrients in the gut lumen is key in coordination of postprandial GI function and alsoin the regulation of food intake. Recent evidence suggests that these pathways can bemodified by long term changes in diet or by inflammatory processes in the gut wall.Thus it is important to determine the cellular and molecular mechanisms underlyingthese processes not only to increase our understanding of as part of basic physiologybut also to understand changes in these pathways that occur in the presence ofpathophysiology and disease. This review summarizes some of the latest data that wehave obtained, together with information from the other laboratories, which haveelucidated some of the mechanisms involved in nutrient detection in the gut wall. Thefocus is on monosaccharides and protein hydrolysates as there is some evidence fora role for nutrient transporters in detection of these nutrients (AU)

No disponible

Evaluación de la citotoxicidad de la aflatoxina y la fumonisina en células intestinales de porcino / Evaluation of the cytotoxicity of AFB1, FB1 and AFB1/FB1 in intestinal cell

La coexistencia de la aflatoxina (AFB) y la fumonisina (FB) es ampliamenteconocida en muchas partes del mundo; sin embargo existen pocos estudiosque describan el efecto sinérgico de ambas micotoxinas in vivo o in vitro. Elobjetivo de este trabajo fue evaluar la citotoxicidad y el efecto de AFB y FBsobre la morfología, la capacidad proliferativa celular y la síntesis deinterleucina 8 (IL-8) en una línea celular de epitelio intestinal porcino (IPEC-1).Respecto a la morfología celular, ésta se vio afectada únicamente en lasconcentraciones más altas de AFB (50 μM) y FB (500 μM). Sin embargo laproliferación celular, el daño celular y la síntesis de IL-8 se vieron afectadascon la combinación AFB/FB (1,3/3,7; 2/3,7 y 5/10 μM, respectivamente), alcompararlas con el efecto individual de estas micotoxinas a las mismasconcentraciones (p < 0,05). Nuestros datos indican que la combinaciónAFB/FB en concentraciones bajas muestra un efecto sinérgico, alterando lamorfofisiología de las células utilizadas, lo que puede implicar, in vivo, laentrada de otras toxinas o agentes biológicos al estar alterada la barreraintestinal, impactando negativamente en la salud humana o animal(AU)

The coexistence of the aflatoxin (AFB) and fumonisin (FB) has been widelydocumented in many parts of the world. However, few studies describing thesynergy effect of both mycotoxins in vivo and/or in vitro are available. Theobjective of this study consisted on evaluating the effect of AFB and FB onthe morphology, the capacity of cellular proliferation, cytotoxicity andinterleukina-8 (IL-8) synthesis in a porcine intestinal epithelial cell line (IPEC-1).Concerning to the cellular morphology it was only affected in theconcentrations higher of AFB (50 μM) and FB (500 μM). However, the cellularproliferation, the cellular damage and synthesis of IL-8 they were affectedwhen present in combination the AFB/FB (1.3/3.7; 2/3.7 and 5/10 μMrespectively) with that showed by the individual effect of similar concentrationsof these mycotoxins (p < 0.05). Our data indicate that the combination ofAFB/FB in low concentrations showed a synergy effect, altering the cellularmorfophisiology, which can imply in vivo the entrance of other toxins orbiological agents for alteration of the intestinal barrier impacting negatively inthe human or animal health(AU)