Study of the intestinal inflammation model induced by TNBS in Zebrafish larvae (Danio rerio).

As doenças inflamatórias intestinais são caracterizadas por uma desregulação na resposta imune contra a microbiota. O zebrafish, tem emergido como um novo modelo para o estudo de doenças inflamatórias. Os ácidos graxos de cadeia curta (AGCCs) são produtos da microbiota intestinal, que possuem papéis antiinflamatórios e aparecem como uma das possíveis terapias contra doenças inflamatórias. A implementação do modelo de inflamação intestinal induzido pelo ácido trinitrobenzenesulfônico (TNBS) em larvas de zebrafish aumentou a mortalidade de forma dose-dependente. Se observou dilatação do lúmen com alisamento das vilosidades intestinais. Não se detectaram mudanças na produção de muco nem no número de células caliciformes mas teve um leve aumento da apoptóse e diminuição da proliferação, nos expostos ao TNBS. Teve aumento de células mielóides infiltrantes e de citocinas inflamatórias, assim como disbiose da microbiota. O tratamento com AGCCs gero alta mortalidade a concentrações acima de 10 mM, mas existe ação anti-inflamatória a esta mesma concentração.Inflammatory bowel diseases are characterized by a dysregulation in immune response against microbiota. The zebrafish has emerged as a new model for the study of inflammatory diseases. Short chain fatty acids (SCFAs) are products of the intestinal microflora, which have anti-inflammatory roles and appear as a possible therapy against inflammatory diseases. The implementation of intestinal inflammation model induced by trinitrobencenesulfonic acid (TNBS) in zebrafish larvae, increased mortality in a dose-dependent manner. Was observe dilatation lumen and straightening of the intestinal villi. No changes were detected in the production of mucus or in the number of goblet cells but had a slight increase in apoptosis and decreased proliferation in exposed to TNBS. Also has, increased cytokines and infiltrating myeloid cells, and dysbiosis of the microbiota. Treatment with SCFAs generate high mortality above 10 mM concentrations, but there anti-inflammatory action to this same concentration

Role of the microbiota in low-grade inflammation induced by a high-fat diet in adult zebrafish thesis Ph. D. thesis in Immunology

O consumo de dietas ricas em gorduras e carboidratos, e um estilo de vida sedentário são fatores que podem levar ao desenvolvimento da obesidade. A obesidade é caracterizada pelo acúmulo excessivo de gordura corporal e está associada a um estado de inflamação crônica de baixo grau, com participação de infiltrado inflamatório no tecido adiposo e liberação sistêmica de citocinas pró-inflamatórias. A microbiota tem sido apontada como um dos principais fatores na patogênese da obesidade, pois animais <i>germ-free(GF) </i> apresentam menor capacidade de captação de energia no intestino do que animais convencionais (CV), participando da indução do ganho de peso. A disbiose gerada durante a obesidade está ligada ao aumento da permeabilidade da parede intestinal, levando a um maior influxo de lipopolissacarídeos (LPS) no sangue, causando endotoxemia e inflamação sistêmica. O <i>zebrafish</i> surge como um modelo interessante para o estudo de doenças imuno- metabólicas e da microbiota, devido ao seu pequeno tamanho e fácil manipulação, capacidade de gerar animais <i>germ-freee</i> resposta metabólica semelhante à dos mamíferos. Desta forma nos propomos a hipótese de que a microbiota de animais sujeitos a uma dieta hiperlipidica é necessária para induzir inflamação de baixo grau nestes animais. Neste estudo, estabelecemos um novo modelo de ganho de peso alimentando <i>zebrafish</i> adultos com uma dieta caseira rica em gorduras. O impacto da microbiota na inflamação de baixo grau foi analisado nestes animais. Ao final de um período de 6 semanas, observamos um aumento significativo de peso nos animais com dieta hiperlipídica (<i>high fat diet</i> - HFD) comparados com animais do grupo controle (normal diet - ND), bem como maior glicemia basal, acúmulo de lipídios no fígado e aumento da gordura visceral e subcutânea, assim como aumento de triglicerídeos e valores de colesterol. O grupo HFD apresentou aumento do infiltrado de células imunes no intestino e aumento de citocinas inflamatórias em comparação ao ND. Animais HFD myd88-/- apresentaram maior ganho de peso que os animais selvagens. Peixes HFD mostraram diminuição de genes de proteínas de junções estreitas, translocação bacteriana no intestino e disbiose intestinal com aumento dos Firmicutes. Análise <i>in silico </i>indicou ativação da via do HIF induzida pela microbiota, sendo também aumentado em animais HFD. Em conclusão, a administração de uma dieta hiperlipídica por 6 semanas reproduz um modelo de ganho de peso no <i>zebrafish</i> com características de síndrome metabólica, inflamação de baixo grau e disbiose da microbiota intestinal com ativação da via do HIF no intestino dos animais HFD.The consumption of diets rich in fats and carbohydrates, and a sedentary lifestyle are factors that can lead to the development of obesity. Obesity is characterized by excessive accumulation of body fat and is associated with a state of low-grade chronic inflammation, with the participation of inflammatory infiltrate in adipose tissue and systemic release of pro- inflammatory cytokines. The microbiota has been identified as one of the main factors in the pathogenesis of obesity, since germ-free (GF) animals have less capacity to capture energy in the intestine than conventional animals (CV), participating in the induction of weight gain. The dysbiosis generated during obesity is linked to the increased permeabilization of the intestinal wall, leading to a greater influx of lipopolysaccharide (LPS) in the blood, causing endotoxemia and systemic inflammation. The zebrafish emerges as an interesting model for the study of immuno-metabolic and microbiota diseases, due to its small size and easy manipulation, ability to generate germ-free animals and metabolic response similar to that of mammals. Thus, we propose the hypothesis that the microbiota of animals subject to a high-fat diet is necessary to induce low-grade inflammation in these animals. In this study, we established a new model of weight gain by feeding zebrafish adults with a homemade high-fat diet. The impact of the microbiota on low-grade inflammation was analyzed in these animals. At the end of a 6-week period, we observed a significant increase in weight in animals with a high fat diet (HFD) compared to animals in the control group (normal diet - ND), as well as higher basal glycemia, accumulation of lipids in the liver and increased visceral and subcutaneous fat, as well as increased triglycerides and cholesterol values. The HFD group showed an increase in the infiltration of immune cells in the intestine and an increase in inflammatory cytokines compared to ND. HFD myd88-/- animals showed greater weight gain than wild-type animals. HFD fish showed decreased genes of tight junctions proteins, bacterial translocation in the intestine and intestinal dysbiosis with increased Firmicutes. <i>In silico</i> analysis indicated activation of the HIF pathway induced by the microbiota, which was also increased in HFD animals. In conclusion, the administration of a hyperlipidic diet for 6 weeks reproduces a model of weight gain in zebrafish with characteristics of metabolic syndrome, low grade inflammation and dysbiosis of the intestinal microbiota with activation of the HIF pathway in the intestines of HFD animals

Intestinal barrier and gut microbiota: Shaping our immune responses throughout life.

The gastrointestinal (GI) tract is considered the largest immunological organ in the body having a central role in regulating immune homeostasis. Contrary to earlier belief, the intestinal epithelial barrier is not a static physical barrier but rather strongly interacts with the gut microbiome and cells of the immune system. This intense communication between epithelial cells, immune cells and microbiome will shape specific immune responses to antigens, balancing tolerance and effector immune functions. Recent studies indicate that composition of the gut microbiome affects immune system development and modulates immune mediators, which in turn affect the intestinal barrier. Moreover, dysbiosis may favor intestinal barrier disruption and could be related to increased susceptibility to certain diseases. This review will be focused on the development of the intestinal barrier and its function in host immune defense and how gut microbiome composition throughout life can affect this role.info:eu-repo/semantics/publishe

Short chain fatty acids (SCFAs) improves TNBS-induced colitis in zebrafish

The short-chain fatty acids (SCFAs) are metabolites originated from the fermentation of dietary fibers and amino acids produced by the bacteria of the intestinal microbiota. The most abundant SCFAs, acetate, propionate, and butyrate, have been proposed as a treatment for inflammatory bowel diseases (IBDs) due to their anti-inflammatory properties. This work aimed to analyze the effects of the treatment of three combined SCFAs in TNBS-induced intestinal inflammation in zebrafish larvae. Here, we demonstrated that SCFAs significantly increased the survival of TNBS-exposed larvae, preserved the intestinal endocytic function, reduced the expression of inflammatory cytokines and the intestinal recruitment of neutrophils caused by TNBS. However, SCFAs treatment did not appear to avoid TNBS-induced tissue damage in the intestinal wall and did not restore the number of mucus-producing goblet cells. Finally, exposure to TNBS induced dysbiosis of the microbiota with an increase in Betaproteobacteria and Actinobacteria, while the treatment with SCFAs maintained these population levels similar to control. Thus, we demonstrate that the treatment of three combined SCFAs presented anti-inflammatory properties previously seen in mammals, opening an opportunity to use zebrafish to explore the potential benefit of these and other metabolites to treat inflammation.info:eu-repo/semantics/publishe