Gut microbiome stability and resilience: elucidating the response to perturbations in order to modulate gut health.

The human gut microbiome is a complex ecosystem, densely colonised by thousands of microbial species. It varies among individuals and depends on host genotype and environmental factors, such as diet and antibiotics. In this review, we focus on stability and resilience as essential ecological characteristics of the gut microbiome and its relevance for human health. Microbial diversity, metabolic flexibility, functional redundancy, microbe-microbe and host-microbe interactions seem to be critical for maintaining resilience. The equilibrium of the gut ecosystem can be disrupted by perturbations, such as antibiotic therapy, causing significant decreases in functional richness and microbial diversity as well as impacting metabolic health. As a consequence, unbalanced states or even unhealthy stable states can develop, potentially leading to or supporting diseases. Accordingly, strategies have been developed to manipulate the gut microbiome in order to prevent or revert unhealthy states caused by perturbations, including faecal microbiota transplantation, supplementation with probiotics or non-digestible carbohydrates, and more extensive dietary modifications. Nevertheless, an increasing number of studies has evidenced interindividual variability in extent and direction of response to diet and perturbations, which has been attributed to the unique characteristics of each individual's microbiome. From a clinical, translational perspective, the ability to improve resilience of the gut microbial ecosystem prior to perturbations, or to restore its equilibrium afterwards, would offer significant benefits. To be effective, this therapeutic approach will likely need a personalised or subgroup-based understanding of individual genetics, diet, gut microbiome and other environmental factors that might be involved.

Fecal carriage of vanB antibiotic resistance gene affects adipose tissue function under vancomycin use.

Detrimental consequences of antibiotic treatment may include long-lasting disruption of the gut microbiota. Previous studies found no negative effects of antibiotics on metabolic health, although individualized responses were observed. Here, we aimed to investigate the subject-specific response to vancomycin use in tissue-specific insulin sensitivity by stratifying individuals based on the presence of antibiotic resistance genes (ARGs) or opportunistic pathogens (OPs) in the baseline fecal microbiota. Quantitative Polymerase Chain Reaction (qPCR) was used to detect ARGs and OPs in DNA isolated from fecal samples of 56 males with overweight/obesity (Body Mass Index: 25-35 kg/m2) and impaired glucose metabolism (fasting plasma glucose ≥5.6 mmol/L and/or 2-hour glucose 7.8-11.1 mmol/L). A two-step hyperinsulinemic-euglycemic clamp was performed to determine tissue-specific insulin sensitivity. Abdominal subcutaneous adipose tissue (AT) gene expression was assessed using Affymetrix microarray. Gut microbial composition was determined using the Human Intestinal Tract Chip (HITChip) microarray. At baseline, the vancomycin resistance gene vanB was present in 60% of our population. In individuals that were vanB-negative at baseline, AT insulin sensitivity (insulin-mediated suppression of plasma free fatty acids) improved during vancomycin use, while it decreased among vanB-positive individuals (% change post versus baseline: 14.1 ± 5.6 vs. -6.7 ± 7.5% (p = .042)). The vancomycin-induced increase in AT insulin sensitivity was accompanied by downregulation of inflammatory pathways and enrichment of extracellular matrix remodeling pathways in AT. In the vanB-positive group, well-known vanB-carrying bacteria, Enterococcus and Streptococcus, expanded in the gut microbiome. In conclusion, microbiome composition and adipose tissue biology were differentially affected by vancomycin treatment based on fecal vanB carriage.

PERDA ELETROLÍTICA DE CÁLCIO, MAGNÉSIO E FERRO NO SUOR DURANTE CORRIDA EM ESTEIRA / ELECTROLYTIC LOSS OF CALCIUM, MAGNESIUM AND IRON IN THE SWEAT DURING RUNNING IN A TREADMILL / PÉRDIDA ELECTROLÍTICA DE CALCIO, MAGNESIO Y HIERRO EN EL SUDOR DURANTE CARRERA EN CINTA RODANTE

RESUMO Introdução: O suor e sua consequente evaporação são fundamentais para manutenção da temperatura corporal durante o exercício. Objetivo: Avaliar a perda de cálcio (Ca++), magnésio (Mg++) e ferro (Fe++) no suor de corredores e de indivíduos ativos. Métodos: Foram avaliados 15 atletas corredores de fundo {VO2máx = 68 ± 5,4 ml(kg.min)-1} e 15 indivíduos ativos não atletas {VO2máx = 50,3 ± 6,3 ml(kg.min)-1}, com média de idade, respectivamente, de 25,3 ± 2,4 e 23,1 ± 4,3 anos. Ambos os grupos se exercitaram por 80 minutos em esteira, com intensidade de 75% a 85% da frequência cardíaca de reserva, e ingeriram 3 ml de água/kg de peso corporal a cada 15 minutos. As condições ambientais da prova foram 21,9 ± 1,5 °C e 89,2 ± 5,6% de umidade relativa para os atletas e 21,8 ± 1,6 °C e 93,2 ± 3,5% de UR para os ativos. As amostras de suor foram coletadas em intervalos regulares de 20 minutos nas regiões do peito, torácica e lombar das costas, para posterior análise dos minerais Ca++, Mg++ e Fe++ por espectrofotômetro de absorção atômica. Resultados: Não foram registradas diferenças significativas para os minerais em função do nível de condicionamento. Observou-se tendência à diminuição na concentração do Mg++ e Fe++ do suor ao longo do exercício. Conclusão: Nas condições ambientais e de exercício estudadas, o condicionamento não interfere na perda de Ca++, Mg++ e Fe++.

ABSTRACT Introduction: Sweat and its consequent evaporation are essential for maintaining body temperature during the exercise. Objective: To evaluate the loss of calcium (Ca++), magnesium (Mg++) and iron (Fe++) in the sweat of runners and active individuals. Methods: Fifteen long-distance-runners {VO2máx = 68 ± 5.4 ml (kg.min)-1} and 15 non- athletes active subjects {VO 2máx = 50.3 ± 6.3 ml (kg.min)-1} with mean ages of 25.3 ± 2.4 and 23.1 ± 4.3 years, respectively. Both groups exercised for 80 minutes on a treadmill, with intensity of 75-85% of reserve heart rate, and ingested 3 ml of water/kg of body weight every 15 minutes. The environmental conditions of the test were 21.9 ± 1.5 °C and 89.2 ± 5.6% relative humidity for athletes and 21.8 ± 1.6 °C and 93.2 ± 3.5% RH for active individuals. The sweat samples were collected at regular intervals of 20 minutes in the chest, thoracic and lower back regions for further analysis of the minerals Ca++, Mg++ and Fe++ by atomic absorption spectrophotometer. Results: No significant differences were recorded for the minerals in relation to fitness level. There was a tendency for a decrease in Mg++ and Fe++ concentrations of sweat over the course of the exercise. Conclusion: In the environmental and exercise conditions studied, the conditioning does not interfere in the loss of Ca++, Mg++ and Fe++.

RESUMEN Introducción: El sudor y su consecuente evaporación son esenciales para mantener la temperatura corporal durante el ejercicio. Objetivo: Evaluar la pérdida de calcio (Ca++), magnesio (Mg++) y hierro (Fe++) en el sudor en corredores y personas activas. Métodos: Se evaluaron 15 corredores de larga distancia {VO2máx = 68 ± 5,4 ml (kg.min)-1} y 15 individuos activos no atletas {VO 2 máx = 50,3 ± 6,3 ml (kg.min)-1}, con promedio de edades de, respectivamente, 25,3 ± 2,4 e 23,1 ± 4,3 años. Ambos grupos hicieron ejercicio durante 80 minutos en una cinta rodante con una intensidad del 75% al 85% de la frecuencia cardíaca de reserva, siendo hidratados con 3 ml de agua/Kg de peso corporal cada 15 minutos. Las condiciones ambientales de la prueba fueron 21,9 ± 1,5 °C y 89,2 ± 5,6% de humedad relativa para los atletas y 21,8 ± 1,6 °C y 93,2 ± 3,5% de HR para los sujetos activos. Las muestras de sudor se recogieron a intervalos regulares de 20 minutos en las regiones del pecho, torácica y lumbar de la espalda para el análisis del Ca++, Mg++y Fe++ por espectrofotometría de absorción atómica. Resultados: No se observaron diferencias significativas para los minerales en función del nivel de acondicionamiento. Hubo una tendencia a la disminución de la concentración de Mg++ y Fe++ en el sudor durante el ejercicio. Conclusión: En el ejercicio estudiado y las condiciones ambientales, el acondicionamiento no interfiere en la pérdida de Ca++, Mg++ y Fe++.