Microbiota intestinal y salud en humanos: obesidad y diabetes mellitus tipo 2 / Gut microbiota and healthy in human: obesity and type 2 diabetes mellitus

RESUMEN Introducción La cantidad y la diversidad bacteriana intestinal están relacionadas con las enfermedades metabólicas e inflamatorias. El objetivo de este trabajo fue caracterizar la composición de la microbiota intestinal en heces y su relación con variables bioquímicas y el patrón de consumo de alimentos en individuos sanos, obesos y pacientes con diabetes mellitus tipo 2, en Mallorca (España). Métodos Las bacterias en heces se caracterizaron por PCR tiempo real. El ADN se aisló a partir de sujetos sanos (23), obesos (no diabéticos) (24) y diabéticos tipo 2 (no obesos) y se amplificó con cebadores específicos para identificar Roseburia, Clostridium leptum, Lactobacillus y Clostridium coccoides-Eubacterium rectale (Firmicutes); Prevotella y Bacteroides (Bacteroidetes); Bifidobacterium (Actinobacteria) y el cebador Universal (para total de bacterias), para la amplificación de la región V4 del gen 16S rRNA. Los resultados se analizaron estadísticamente utilizando SPSS v.21. Resultados En una población rural y urbana de Baleares, se detectaron niveles de insulina significativamente superiores en obesos (12,2 + 1,3 md/dL). En diabéticos, los niveles de triglicéridos, glucosa en sangre, hemoglobina glucosilada y albúmina en orina fueron superiores que en controles y obesos (por encima del rango normal). La mayor dispersión de las variables bioquímicas en sangre se identificó con: Clostridium coccoide-Eubacterium rectale, Bacteroides y Bifidobacterium, como posibles marcadores en obesos y diabéticos y Prevotella y Lactobacillus, como marcadores de salud. El contenido total de bacterias es mayor en controles y la relación entre reinos bacterianos es menor en este grupo. Los patrones de consumo de alimentos fueron diferentes en los tres grupos lo cual está relacionado con la variación en los patrones bacterianos. Conclusión La variabilidad en el consumo de alimentos estuvo relacionada con cinco marcadores bacterianos principales que contribuyeron a la mayor variabilidad de marcadores bioquímicos entre grupos de sujetos: Clostridium coccoide-Eubacterium rectale, Bacteroides, Bifidobacterium, Prevotella y Lactobacillus, en una población de Mallorca (España). Gut microbiota and healthy in human: obesity and type 2 diabetes mellitus.

ABSTRACT Introduction The amount and bacterial diversity in the bowel are associated to metabolic and inflammatory diseases. The aim was to characterize the gut microbiota composition in faeces and food consumption pattern in healthy, obese and Type 2 diabetes mellitus subjects from Majorca (Spain). Methods Bacteria in faeces were characterized by Real-time PCR. DNA was isolated from healthy subjects (23), obese patients (not diabetic) (24) and type 2 diabetic patients (12) and amplified with specific primers for the identification of Roseburia, Clostridium leptum, Lactobacillus and Clostridium coccoides-Eubacterium rectale (Firmicutes); Prevotella and Bacteroides (Bacteroidetes); Bifidobacterium (Actinobacteria); and Universal primer (for all bacteria), referred to amplification of 16S rRNA gene V4 region. Results were statistically analyzed by SPSS v.21. Results A rural and urban population from Balearic Islands was tested. The insulin levels were highest in obese group (12.2 + 1.3 md/dL) while the triglyceride, blood glucose, glycosylated haemoglobin and urine albumin levels were highest in diabetic group. The major dispersion of the blood variables was identified to a bacteria core: Clostridium coccoide-Eubacterium rectale, Bacteroides and Bifidobacterium as possible markers for obese and diabetic patients; and Prevotella and Lactobacillus levels as markers of health. The total amount of bacteria is the highest in control group, such as the ratio between phyla is the lowest. The food consumptiom patterns were different among which is related to the variation in the bacterial patterns. Conclusion The variability in the foods consumption among groups was related to five bacterial markers which contributed to the major variability in blood markers: Clostridium coccoide-Eubacterium rectale, Bacteroides, Bifidobacterium, Prevotella y Lactobacillus; in a population from Majorca, Spain.

The serum levels of 17beta-estradiol, progesterone and triiodothyronine correlate with brown adipose tissue thermogenic parameters during aging.

Sex and thyroid hormones are among the factors modulating energy metabolism through regulation of mitochondrial oxidative capacity. Brown adipose tissue (BAT) in old female rats has been shown to maintain, better than males, the ability to produce heat when exposed to cold. Considering the decline that takes place in gonadal and thyroid function during aging, the aim of this work was to test whether the age-related hormonal status may be a potential mediator of the gender differences in BAT decline. COX activity, UCP1, mitochondrial respiration rate, mitochondrial DNA (mtDNA), levels of mitochondrial transcription factor A (TFAM), as well as the serum levels of sex steroids (17beta-estradiol, progesterone and testosterone) and thyroid hormones (T3 and T4) were measured in 6-, 18-, and 24-month (mo) old male and female rats kept at 22 degrees C. Six mo-old female rats showed higher thermogenic features than males. Male rats at 18-mo showed a decrease in uncoupling activity compared to females. Both genders showed marked signs of atrophy in BAT of 24-mo-old rats, characterized by a decrease in total DNA, mitochondrial protein, COX and UCP1, whereas mtDNA was found to increase. Sex steroid hormones were well correlated with BAT parameters when both genders were considered, however, T3 was the hormone with the strongest positive correlations in female rats. In conclusion, our findings provide evidence suggesting that T3 may be a potential mediator of the sexual dimorphism in the effect of aging on the functional decline of BAT.

Caloric restriction retards the age-related decline in mitochondrial function of brown adipose tissue.

Caloric restriction (CR) has been shown to prevent the age-associated loss of mitochondrial function and biogenesis in several tissues such as liver, heart, and skeletal muscle. However, little is known about the effects of CR on a tissue in which the mitochondria have no adenosine triphosphate (ATP)-producing purpose but show a high degree of uncoupling, namely brown adipose tissue (BAT). Hence, the aim of the present study was to analyze the effect of long-term CR on BAT mitochondrial function and biogenesis. BAT mitochondria obtained from 24-month-old male and female rats previously subjected to 40% CR for 12 months were compared with mitochondria from old (24 months) and young (6 months) ad libitum fed rats. Old restricted rats compared to old ad libitum fed ones showed a reduction in BAT size with respect to fat content and adipocyte number. Mitochondrial DNA content in BAT increased with age and even more so in restricted rats, indicating a summative effect of age and CR on mitochondrial proliferation. CR induced resistance to lose total and mitochondrial protein, COX activity, and uncoupling capacity with advancing age, in relation with a lower decrease of mitochondrial transcription factor A (TFAM). In summary, our results demonstrate CR prevents the age-associated decline in mitochondrial function in BAT, probably in relation with a lower impairment of mitochondrial biogenesis.

Genomic modulation of mitochondrial respiratory genes in the hypertrophied heart reflects adaptive changes in mitochondrial and contractile function.

We hypothesized the coordinate induction of mitochondrial regulatory genes in the hypertrophied right ventricle to sustain mitochondrial respiratory capacity and contractile function in response to increased load. Wistar rats were exposed to hypobaric hypoxia (11% O(2)) or normoxia for 2 wk. Cardiac contractile and mitochondrial respiratory function were separately assessed for the right and left ventricles. Transcript levels of several mitochondrial regulators were measured. A robust hypertrophic response was observed in the right (but not left) ventricle in response to hypobaric hypoxia. Mitochondrial O(2) consumption was increased in the right ventricle, while proton leak was reduced vs. normoxic controls. Citrate synthase activity and mitochondrial DNA content were significantly increased in the hypertrophied right ventricle, suggesting higher mitochondrial number. Transcript levels of nuclear respiratory factor-1, peroxisome proliferator-activated receptor-gamma-coactivator-1alpha, cytochrome oxidase (COX) subunit II, and uncoupling protein-2 (UCP2) were coordinately induced in the hypertrophied right ventricle following hypoxia. UCP3 transcript levels were significantly reduced in the hypertrophied right ventricle vs. normoxic controls. Exposure to chronic hypobaric hypoxia had no significant effects on left ventricular mitochondrial respiration or contractile function. However, COXIV and UCP2 gene expression were increased in the left ventricle in response to chronic hypobaric hypoxia. In summary, we found coordinate induction of several genes regulating mitochondrial function and higher mitochondrial number in a model of physiological right ventricular hypertrophy, linking the efficiency of mitochondrial oxidative phosphorylation and respiratory function to sustained contractile function in response to the increased load.

Gender-related differences in morphology and thermogenic capacity of brown adipose tissue mitochondrial subpopulations.

To investigate the possible existence of a gender dimorphism in the morphology and functionality of brown adipose tissue (BAT) mitochondrial subpopulations, we obtained three mitochondrial fractions - heavy, medium and light - by differential centrifugation. Electron microscopic analysis was carried out and mitochondrial protein content, cytochrome c oxidase and ATP synthase activities, mitochondrial DNA content and UCP1 protein levels were measured in each mitochondrial fraction. Female rats showed a greater mitochondrial size than males, with a different distribution pattern of the subpopulations. These differences were accompanied by higher oxidative and thermogenic capacities and a higher protein content in female rat BAT. This tissue also showed a greater tendency to respiratory chain uncoupling, as well as a close coordination between the oxidative, phosphorylative and thermogenic processes. These differences were found in the heavy subpopulation but not in the light one. Our results demonstrate that female rat BAT shows a highly differentiated mitochondrial pool, with the heavy mitochondrial subpopulation as the main responsible for the greater thermogenic activity of this tissue. In addition, it seems that there is a differential regulation of the mitochondrial growth cycle between genders in BAT, which leads to enhanced thermogenic capacity in female rat mitochondria.

Skeletal muscle changes in patients with obstructive sleep apnoea syndrome.

Previous studies have shown that chronic hypoxia leads to changes in skeletal muscle structure (fibre size and type) and activities of several bioenergetic enzymes. Whether this occurs also in conditions characterised by intermittent hypoxia, such as the obstructive sleep apnoea syndrome (OSAS), is unknown. To explore this possibility, we obtained a needle biopsy of the quadriceps femoris in 12 consecutive stable outpatients with severe OSAS (52 +/- 9 year, apnoea-hypopnoea index 70 +/- 14 h(-1)) (x +/- SD) and in six healthy volunteers (49 +/- 8 year), where we quantified fibre type, size and protein content, as well as phosphofructo-kinase (PFK) and cytochrome oxidase (CytOx) activities. We found that fibre-type distribution was similar in patients and controls. In contrast, the diameter of type II fibres (74 +/- 10 microm vs. 56 +/- 11 microm, P < 0.05) and protein content (100 +/- 14 vs. 88 +/- 8 microg/mg) was higher in patients with OSAS. Likewise, we observed upregulation of CytOx (0.93 +/- 0.38 vs. 0.40 +/- 0.22 microkat/mg protein, P < 0.01) and PFK activities (5.35 +/- 4.8 vs. 1.3 +/- 1.3 microkat/ mg protein, P < 0.05) in patients with OSAS. These results show that, paralleling which occurs in conditions characterised by continuous hypoxia, patients with OSAS (and intermittent hypoxia) also show structural and bioenergetic changes in their skeletal muscle.