Human gut microbiota plays an important role in individual health. When the balance between host and gut microbiota is disrupted, changes in microbiota composition and function occur, which is referred as dysbiosis. Environmental factors as diet, proton pump inhibitors, and antibiotics can lead to a permanent dysbiotic disruption. Clarification of these imbalances was made possible by recent advances in genome sequencing methods that supported acknowledgment of the interplay between microbiome and intestinal and extraintestinal disorders. This review focuses on the microbiota impact in inflammatory bowel disease, gastric cancer, colorectal cancer, nonalcoholic fatty liver disease (NAFLD), irritable bowel syndrome (IBS), and Clostridium difficile infection (CDI). Furthermore, novel therapies are summarized. Fecal microbiota transplant (FMT) is a successful and established therapy in recurrent CDI, and its application in other dysbiosis-related diseases is attracting enormous interest. Pre- and probiotics target microbial rebalance and have positive effects mainly in NAFLD, ulcerative colitis, IBS, and CDI patients. Promising anticarcinogenic effects have also been demonstrated in animal models. The literature increasingly describes microbial changes in many dysbiotic disorders and shows what needs to be treated. However, probiotics and FMT application in clinical practice suffers from a shortage of randomized controlled trials with standardized therapy regimens to support their recommendation.

A microbiota gastrointestinal desempenha um papel essencial na saúde humana. Quando surge um desequilíbrio entre esta e o hospedeiro, ocorrem alterações na composição e função da microbiota que se designa de disbiose. Fatores ambientais como a dieta, inibidores da bomba de protões e antibióticos podem induzir um estado disbiótico permanente. O esclarecimento destas desregulações foi possível graças a avanços recentes nos métodos de sequenciação genómica que, por sua vez, nos ajudaram a perceber a interação entre a microbiota e distúrbios intestinais e extra-intestinais. Esta revisão foca-se no impacto da microbiota na Doença Inflamatória Intestinal, Cancros gástrico e colorretal, Fígado Gordo Não-Alcoólico (FGNA), Síndroma do Intestino Irritável (SII) e Infeção por Clostridium difficile(ICD). Além disso, resume-se no final as estratégias terapêuticas que têm surgido. O transplante fecal é um tratamento com eficácia estabelecida na infeção recorrente por C. difficile, reunindo um crescente interesse na sua aplicação em outras doenças relacionadas com disbiose. Os pre- e probióticos promovem o reequilíbrio microbiano e têm evidência de efeitos positivos sobretudo no FGNA, Colite Ulcerosa, SII e ICD. Em modelos animais, estes também demonstraram efeitos anti-carcinogénicos promissores. É evidente na literatura uma descrição cada vez mais pormenorizada das alterações microbianas em vários distúrbios disbióticos, oferecendo ferramentas que permitem saber o que pode ser tratado. No entanto, a aplicação de probióticos e transplante fecal na prática clínica sofre ainda de carência de ensaios clínicos randomizados, com regimes terapêuticos standard, em número que permita a sua recomendação formal.

Palavras Chave Microbiota, Disbiose, Doenças associadas a disbiose, Probióticos, Transplante de microbiota fecal

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