Gut microbiota in Mexican patients with common variable immunodeficiency

Introduction: Common variable immunodeficiency (CVID) is the main symptomatic primary immunodeficiency and is associated with complex immune disorders. Gut microbiota interacts closely with the immune system, and intestinal dysbiosis is related to multiple diseases. Objective: To describe for the first time the composition of gut microbiota in Mexican patients with CVID. Methods: Fecal samples from five patients with CVID were collected and massive sequencing of the V3-V4 region of 16S rRNA gene was carried out using illumina technology. Results: Bacterial relative abundance was observed at all taxonomic levels. Firmicutes, Actinobacteria and Verrucomicrobia were the predominant phyla. The Clostridia class and the Clostridial order were the most common in their respective taxon; the Ruminococcaceae family predominated. A total of 166 genera were reported, with the most abundant being Faecalibacterium. Five species were identified, but only Bifidobacterium longum was present in all patients. Conclusions: Unlike healthy subjects' gut microbiota, where Firmicutes and Bacteroidetes predominate, the microbiota of the patients with CVID considered in this study was abundant in Firmicutes, Actinobacteria and Verrucomicrobia. The low presence of Bacteroidetes and high abundance of Firmicutes might indicate the existence of intestinal dysbiosis in these patients.

The pulmonary microbiome: challenges of a new paradigm / Microbioma pulmonar: desafios de um novo paradigma

ABSTRACT The study of the human microbiome-and, more recently, that of the respiratory system-by means of sophisticated molecular biology techniques, has revealed the immense diversity of microbial colonization in humans, in human health, and in various diseases. Apparently, contrary to what has been believed, there can be nonpathogenic colonization of the lungs by microorganisms such as bacteria, fungi, and viruses. Although this physiological lung microbiome presents low colony density, it presents high diversity. However, some pathological conditions lead to a loss of that diversity, with increasing concentrations of some bacterial genera, to the detriment of others. Although we possess qualitative knowledge of the bacteria present in the lungs in different states of health or disease, that knowledge has advanced to an understanding of the interaction of this microbiota with the local and systemic immune systems, through which it modulates the immune response. Given this intrinsic relationship between the microbiota and the lungs, studies have put forth new concepts about the pathophysiological mechanisms of homeostasis in the respiratory system and the potential dysbiosis in some diseases, such as cystic fibrosis, COPD, asthma, and interstitial lung disease. This departure from the paradigm regarding knowledge of the lung microbiota has made it imperative to improve understanding of the role of the microbiome, in order to identify possible therapeutic targets and to develop innovative clinical approaches. Through this new leap of knowledge, the results of preliminary studies could translate to benefits for our patients.

RESUMO O estudo do microbioma humano - e, mais recentemente, o do sistema respiratório - através de sofisticadas técnicas de biologia molecular, desvendou a imensa diversidade de colonização microbiana nos seres humanos, sejam saudáveis, sejam portadores de diferentes doenças. Aparentemente, ao contrário do que se acreditava, existe uma colonização não patogênica dos pulmões por microrganismos, como bactérias, fungos e vírus. Esse microbioma pulmonar fisiológico apresenta uma densidade baixa de colônias, porém uma elevada diversidade; por outro lado, alguns estados patológicos levam a uma perda dessa diversidade, com aumento da concentração de alguns gêneros bacterianos em detrimento de outros. Ainda, além do conhecimento qualitativo das bactérias presentes no pulmão em diversos estados de saúde ou de doença, o conhecimento avança para o entendimento da interação que essa microbiota tem com o sistema imune local e sistêmico, modulando a resposta imunológica. Compreendendo essa intrínseca relação entre a microbiota e os pulmões, estudos apresentam novos conceitos sobre os mecanismos fisiopatogênicos da homeostase do sistema respiratório e a possível disbiose em estado de algumas doenças, como fibrose cística, DPOC, asma e doenças intersticiais. Essa quebra de paradigma do conhecimento da microbiota presente nos pulmões fez com que se torne premente entender melhor o papel do microbioma para identificar possíveis alvos terapêuticos e abordagens clínicas inovadoras. Através desse novo salto de conhecimento é que os resultados dos estudos preliminares poderão ser traduzidos em benefícios aos nossos pacientes.