Microbiota en la salud humana: técnicas de caracterización y transferencia

Composition of the microbiota in patients with growth hormone deficiency before and after treatment with growth hormone

INTRODUCTION

Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) have modulatory effects on bowel function and its microbiota. Our aim was to investigate whether low levels of GH and IGF-1 in patients with GH deficiency are associated with changes in gut physiology/integrity as well as in the composition of the gut microbiota.

MATERIALS AND METHODS

We conducted a case-control study in 21 patients with GH deficiency, at baseline and after 6 months of GH treatment, and in 20 healthy controls. We analysed changes in anthropometric and laboratory characteristics and bacterial translocation and studied the composition of the microbiome by means of massive 16S rRNA gene sequencing.

RESULTS

Growth hormone deficiency was accompanied by a significant increase in serum levels of sCD14, a marker of bacterial translocation (P < .01). This increase was reversed by GH treatment. We did not find any differences in the composition or α- or β-diversity of the gut microbiota after treatment or between cases and controls.

CONCLUSIONS

Our work is the first to demonstrate that the presence of GH deficiency is not associated with differences in gut microbiota composition in comparison with healthy controls, and changes in microbiota composition are also not found after 6 months of treatment. However, GH deficiency and low IGF-1 levels were associated with an increase in bacterial translocation, which had reversed after treatment.

Description of the colonizing mycobiota of endotracheal tubes from patients admitted to two intensive care units in Bogotá, Colombia

Introduction. Medical device colonization by pathogenic microorganisms is a risk factor for increasing infections associated with health care and, consequently, the morbidity and mortality of intubated patients. In Colombia, fungal colonization of endotracheal tubes has not been described, and this information could lead to new therapeutic options for the benefit of patients. Objective. To describe the colonizing fungi of the endotracheal tubes from patients in the intensive care unit, along with its antifungal sensitivity profile. Materials and methods. We conducted a descriptive, observational study in two health centers for 12 months. Endotracheal tubes were collected from patients in intensive care units. Samples were processed for culture, fungi identification, and antifungal sensitivity profile assessment. Results. A total of 121 endotracheal tubes, obtained from 113 patients, were analyzed: 41.32 % of the tubes were colonized by Candida albicans (64.62%), C. non‑albicans (30.77%), Cryptococcus spp. (3.08%) or molds (1.54%). All fungi evaluated showed a high sensitivity to antifungals, with a mean of 91%. Conclusion. Fungal colonization was found in the endotracheal tubes of patients under invasive mechanical ventilation. The antifungal sensitivity profile in these patients was favorable. A clinical study is required to find possible correlations between the colonizing microorganisms and infectivity.

Human virome: Implications in cancer

In recent years, the human virome has gained importance, especially after the SARS-CoV-2 pandemic, due to its possible involvement in autoimmune, inflammatory diseases, and cancer. Characterization of the human virome can be carried out by shotgun next-generation sequencing (metagenomics), which allows the identification of all viral communities in an environmental sample and the discovery of new viral families not previously described. Variations in viral quantity and diversity have been associated with disease development, mainly due to their effect on gut bacterial microbiota. Phages can regulate bacterial flora through lysogeny; this is associated with increased susceptibility to infections, chronic inflammation, or cancer. The virome characterization in different human body ecological niches could help elucidate these particles' role in disease. Hence, it is important to understand the virome's influence on human health and disease. The present review highlights the significance of the human virome and how it is associated with disease, focusing on virome composition, characterization, and its association with cancer.

Circulating Levels of Short-Chain Fatty Acids during Pregnancy and Infant Neurodevelopment

BACKGROUND

Short-chain fatty acids (SCFA) play a key role in the gut microbiota-brain crosstalk regulating the main neurodevelopmental processes during pregnancy. The aim of this study is to investigate the longitudinal relationship between prenatal levels of the main SCFAs in maternal serum and infant cognitive development and temperament on day 40 postpartum after adjusting for several pre-, peri- and post-natal confounders.

METHODS

A sample of 357 healthy mother-infant pairs were followed from the beginning of pregnancy to 40 days after birth. Serum SCFA concentrations were assessed in the first and third trimester of pregnancy by LC-MS/MS; and socio-demographic, nutritional, and psychological variables were collected. At 40 days, the Bayley Scales of Infant Development-III and the Early Infancy Temperament Questionnaire were administered.

RESULTS

Lower serum levels of acetic, butyric and isobutyric acid, mainly during the first trimester, were related to better language and psychomotor development and, in the case of butyric acid, better intensity behavior in infants. Medium levels of propionic acid were related to better scores for development, mood and temperament.

CONCLUSIONS

These findings suggest that in a community sample of healthy pregnant women from a Mediterranean region of northern Spain, lower serum levels of SCFAs, especially in the first trimester of pregnancy, seem to be related to better infant neurodevelopment.

Sample Processing for Metaproteomic Analysis of Human Gut Microbiota

Human gut microbiota can be studied through the characterization of microorganisms present in feces. Metaproteomics has arisen as a good approach to investigate this vast community. However, the processing of fecal samples in order to obtain the largest number of proteins from gut microbiota to be subsequently analyzed by means of metaproteomics is a challenge. Here we describe a protocol to approach this task. It includes two main steps: the first step of humectation and dispersion of the feces, followed by the separation of microorganisms from other fecal components such as roughage and food debris, and the second step in which microbial cells are broken up and microbiota proteins recovered for MS analysis. Detailed procedures for sample preparation, protein extraction, trypsin digestion, and mass spectrometry analysis for gut microbiota samples are provided.

Prebiotics, probiotics and fecal microbiota transplantation in autism: A systematic review

In recent years, there has been an increase in studies of the implications of the gut microbiota (GM) in children with autism spectrum disorder (ASD). There is a hypothesis which propose a relationship between the emotional state and the abundance of intestinal microbes through the so-called microbiota-intestine-brain axis. In this sense, dysbiotic GM could be a contributing factor to the appearance of ASD. This systematic review article analyzes the results of the intervention using prebiotics (carrot powder, vitamin A, partially hydrolyzed guar gum, galactooligosaccharides, etc.), probiotics (mainly: Lactobacillus, Bifidobacterium, etc.) and transplantation of fecal microbiota in ASD children. In conclusion, the results of the initial studies suggest changes in ASD symptoms, gastro-intestinal symptoms and GM composition after the interventions. However, the results should be taken with caution because there are very few studies that analyze the efficacy of long-term treatments and the different combinations of them.

Inferring Bacterial Infiltration in Primary Colorectal Tumors From Host Whole Genome Sequencing Data

Colorectal cancer is the third most common cancer worldwide with abysmal survival, thus requiring novel therapy strategies. Numerous studies have frequently observed infiltrating bacteria within the primary tumor tissues derived from patients. These studies have implicated the relative abundance of these bacteria as a contributing factor in tumor progression. Infiltrating bacteria are believed to be among the major drivers of tumorigenesis, progression, and metastasis and, hence, promising targets for new treatments. However, measuring their abundance directly remains challenging. One potential approach is to use the unmapped reads of host whole genome sequencing (hWGS) data, which previous studies have considered as contaminants and discarded. Here, we developed rigorous bioinformatics and statistical procedures to identify tumor-infiltrating bacteria associated with colorectal cancer from such whole genome sequencing data. Our approach used the reads of whole genome sequencing data of colon adenocarcinoma tissues not mapped to the human reference genome, including unmapped paired-end read pairs and single-end reads, the mates of which were mapped. We assembled the unmapped read pairs, remapped all those reads to the collection of human microbiome reference, and then computed their relative abundance of microbes by maximum likelihood (ML) estimation. We analyzed and compared the relative abundance and diversity of infiltrating bacteria between primary tumor tissues and associated normal blood samples. Our results showed that primary tumor tissues contained far more diverse total infiltrating bacteria than normal blood samples. The relative abundance of Bacteroides fragilis, Bacteroides dorei, and Fusobacterium nucleatum was significantly higher in primary colorectal tumors. These three bacteria were among the top ten microbes in the primary tumor tissues, yet were rarely found in normal blood samples. As a validation step, most of these bacteria were also closely associated with colorectal cancer in previous studies with alternative approaches. In summary, our approach provides a new analytic technique for investigating the infiltrating bacterial community within tumor tissues. Our novel cloud-based bioinformatics and statistical pipelines to analyze the infiltrating bacteria in colorectal tumors using the unmapped reads of whole genome sequences can be freely accessed from GitHub at https://github.com/gutmicrobes/UMIB.git.