Structural difference of gut microbiota in obese patients with or without acanthosis nigricans

Abstract

Objective To investigate the distribution of gut microbiota in obese patients with or without acanthosis nigricans. Methods Totally 131 obese patients and 25 healthy participants were divided into three groups: the obesity with acanthosis nigricans (AN) group (n=59), the simple obesity (OB) group (n=79), and the control (CON) group (n=25). The fresh stool samples were collected, and the clinical and biochemistry markers were measured. Pyrosequencing technology was performed based on the 16s rRNA of fecal samples to identify and analyze the distribution pattern of gut microbiota in each group. Results The AN group had significantly higher body mass index[(37.45±5.12)kg/m2vs. (33.34±2.54)kg/m2vs.(20.35±1.68)kg/m2, P=0.045, P<0.001], insulin[32.77(25.18)mU/L vs. 20.73(9.30)mU/L vs. 8.70(6.18)mU/L, P<0.001, P<0.001], insulin resistance[7.78(6.87) vs. 4.71(2.88)vs.1.81(1.40), P<0.001, P<0.001], and interleukin (IL)-6[(3.64±2.23)ng/L vs.(2.71±0.78)ng/L vs.(2.17±0.86)ng/L, P=0.040, P=0.009] levels than OB and CON groups compared with OB and CON groups, AN group had significantly decreased diversity of bacterial flora (P=0.015, P=0.001), while no significant difference was observed in the abundance of bacterial flora. At the phylum level, the composition of flora among these three groups was similar, mainly including bacteroidetes, firmicutes, proteobacteria, and actinomycetes. Although the proportions of main bacteria flora were different, the difference was not statistically significant. At the genus level, the bacteria flora in AN and OB groups were primarily composed of Bacteroides, Megamonas, Faecalibacterium and Escherichia-Shigella. In addition, compared to OB and CON groups, AN group had significantly lower proportion of Ruminococcus (P=0.023, P=0.043, respectively) and higher proportion of Veillonella (P=0.048, P=0.043, respectively). Furthermore, the proportion of Weissella was higher in AN and OB groups than in CON group (P=0.045, P=0.025). Conclusion Obese patients with AN have more severe insulin resistance and inflammation status than those with simple obesity, and the distribution feature of gut microbiota also differ between these two patient populations. Key words: Obesity; Acanthosis nigricans; Enterobacteriaceae; Interleukin-6; 16s rRNA