The pool of microbes inhabiting our body is known as "microbiota" and their collective genomes as "microbiome". The colon is the most densely populated organ in the human body, although other parts, such as the skin, vaginal mucosa, or respiratory tract, also harbour specific microbiota. This microbial community regulates some important metabolic and physiological functions of the host, and drives the maturation of the immune system in early life, contributing to its homeostasis during life. Alterations of the intestinal microbiota can occur by changes in composition (dysbiosis), function, or microbiota-host interactions and they can be directly correlated with several diseases. The only disease in which a clear causal role of a dysbiotic microbiota has been demonstrated is the case of Clostridium difficile infections. Nonetheless, alterations in composition and function of the microbiota have been associated with several gastrointestinal diseases (inflammatory bowel disease, colorectal cancer, or irritable bowel syndrome), as well as extra-intestinal pathologies, such as those affecting the liver, or the respiratory tract (e.g., allergy, bronchial asthma, and cystic fibrosis), among others. Species of Bifidobacterium genus are the normal inhabitants of a healthy human gut and alterations in number and composition of their populations is one of the most frequent features present in these diseases. The use of probiotics, including bifidobacteria strains, in preventive medicine to maintain a healthy intestinal function is well documented. Probiotics are also proposed as therapeutic agents for gastrointestinal disorders and other pathologies. The World Gastroenterology Organization recently published potential clinical applications for several probiotic formulations, in which species of lactobacilli are predominant. This review is focused on probiotic preparations containing Bifidobacterium strains, alone or in combination with other bacteria, which have been tested in human clinical studies. In spite of extensive literature on and research into this topic, the degree of scientific evidence of the effectiveness of probiotics is still insufficient in most cases. More effort need to be made to design and conduct accurate human studies demonstrating the efficacy of probiotics in the prevention, alleviation, or treatment of different pathologies.

OBJECTIVEObesity is associated with a state of chronic low-grade inflammation. Myeloperoxidase (MPO) plays an important role in the initiation and progression of acute and chronic inflammatory diseases, such as cardiovascular disease (CVD). The objectives of the current study were to evaluate plasma MPO levels in prepubertal obese children and to determine whether MPO could be an early biomarker of inflammation and CVD risk.RESEARCH DESIGN AND METHODSIn a prospective multicenter case-control study paired by age and sex of 446 Caucasian prepubertal children ages 6–12 years, 223 normal-weight and 223 obese children were recruited. Blood pressure, waist circumference, weight, and height were measured. In addition to MPO, glucose, insulin, metabolic lipid parameters, oxidized low-density lipoproteins, adiponectin, leptin, resistin, C-reactive protein (CRP), interleukin 6, tumor necrosis factor α, matrix metalloproteinase-9 (MMP-9), and plasminogen activator inhibitor 1 were determined.RESULTSWe found that MPO was elevated in prepubertal obese children and that this enzyme was associated with such proinflammatory and cardiovascular risk biomarkers as CRP, MMP-9, and resistin. Insulin resistance calculated by the homeostatic assessment model was the best predictor of MPO.CONCLUSIONSMPO is an early biomarker of inflammation associated with CVD risk in obese children at the prepubertal age.

Background/Aims: There is a strong debate on the diagnosis and early phenotypic expression of the metabolic syndrome in children. The aim of the present study was to examine the frequency of the metabolic syndrome using various definitions in obese prepubertal and pubertal children. Methods: 478 (213 females and 265 males) obese children were recruited in three provinces of Spain. Blood pressure (BP), waist circumference, and weight and height were measured, and body mass index was calculated. Glucose, insulin, high-density lipoprotein cholesterol and triacylglycerols were determined. We classified the children according to seven different proposed definitions of the metabolic syndrome. Results: Regardless of the definition used, the prevalence of the metabolic syndrome (8.3–34.2%) was relatively high in obese children in the prepubertal period as well as in pubertal children (9.7–41.2%). We performed a principal-factor analysis to explain correlations among features of the metabolic syndrome and found that glucose metabolism (factor 1), dyslipidemia (factor 2) and obesity/BP (factor 3) explained 72% of the total variance. Conclusion: Irrespective of the classification used, the metabolic syndrome is not only present in pubertal but also in prepubertal children. International definitions of the metabolic syndrome should also consider criteria specific for children in the prepubertal period, i.e. children aged <10 years.

Objective: To evaluate the association between waist-to-height ratio (WHtR) and specific biomarkers of inflammation, CVD risk and endothelial dysfunction in prepubertal obese children. Design: Prospective, multicentre case-control study matched by age and sex. Setting: Children were recruited between May 2007 and May 2010 from primarycare centres and schools in three cities in Spain (Cordoba, Santiago de Compostela and Zaragoza). Subjects: Four hundred and forty-six (223 normal weight and 223 obese) Caucasian prepubertal children aged 6-12 years. Results: WHtR was higher in the obese than in the normal-weight children. Blood pressure, waist circumference, weight, height, insulin, plasma lipids, leptin, resistin, abnormal neutrophil and monocyte counts, C-reactive protein, IL-6, IL-8, TNF-a, myeloperoxidase, soluble intercellular adhesion molecule-1, selectin and plasminogen activator inhibitor-1 levels were higher in the obese than in the normal-weight group. Adiponectin and HDL-cholesterol were lower and glucose and metalloproteinase-9 showed no differences. Resistin, TNF-a and active plasminogen activator inhibitor-1 were associated with WHtR, a sensitive indicator of central obesity. Conclusions: Our results lead to the hypothesis that changes in biomarker levels of insulin resistance, inflammation and CVD risk before puberty might induce metabolic consequences of obesity in obese children before reaching adulthood.

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