Comunidade bacteriana em indivíduos eutróficos, com sobrepeso e obesos: estudo da microbiota fecal por abordagem metataxonômica.

Abstract

Obesity today is considered a pandemic affecting people of all ages, sex and race. It is a disease that curves with a chronic inflammatory state of low degree. Its cause is multifactorial and is associated with metabolic complications of high morbidity and mortality that generate high costs to the health system. The human intestinal microbiota (HIM) has great importance in the development of intestinal function. Recent studies have associated HIM with the development and maintenance of obesity involving several distinct mechanisms. The objective of the present study was to evaluate the intestinal bacterial diversity comparatively between eutrophic, overweight and obese individuals, from a database of fecal metagenomic DNA, using a new generation sequencing technique; to correlate the microbial profile with the nutritional, laboratory and anthropometric data previously analyzed. We evaluated 72 individuals classified as eutrophic (n=22), overweight (n=23) and obese (n=21) according to BMI. The rarefaction analysis and the chao-1 index showed that obese individuals have lower species richness compared to the other two groups studied, but no difference in taxonomic composition between the groups was evidenced. Unlike most studies, no statistical difference was found in the abundance of the phylos Firmicutes and Bacteroidetes, nor in the Firmicutes/ Bacteroidetes ratio. A statistically significant difference was found in the phylum Verrucomicrobia between eutrophic and obese. Regarding bacterial genera, the groups of eutrophic and obese individuals differed in relation to the Prevotella (p = 0.0228), Prevotella 1 (p = 0.0291), Prevotella 9 (p = 0.0178), Alistipes (p = 0.0030), Rumicococaceae; Other (p =<0.0001) and Akkermansia (p = 0.0188), the overweight group being similar to the two groups. Between overweight and obese, a statistical difference was found between Alistipes (p = 0.0030), Rumicococaceae; Others (p =<0.0001) and Fecalibacterium (p = 0.0296). No difference was found between eutrophic and overweight groups. The core microbiota of the eutrophic group showed a considerably higher number of OTU's - 188 in total in relation to the overweight group that presented 83 OTU's and the obese group, which in turn presented only 53 OTU's common to the group, again showing greater wealth in the first two groups in relation to the obese. The correlation analysis showed a strong or very strong negative correlation between Firmicutes and Bacteroidetes in the three groups studied, suggesting that the increase in the abundance of one of them makes the intestinal environment unfavorable for the other. Regarding the correlations specifically between metadata and the main bacterial phyla, there was no statistically significant correlation. We concluded that the intestinal microbiota of the obese group has less richness compared to the other two groups, in addition to presenting distinct bacterial structure in relation to specific taxonomic groups and a less diverse core microbiota. Overweight individuals behave in a highly heterogeneous manner with an intermediate intestinal microbiota structure.