title: Insulin resistance is associated with specific gut microbiota in appendix samples from morbidly obese patients.
abstract: Alterations in intestinal microbiota composition could promote a proinflammatory state in adipose tissue that is associated with obesity and insulin resistance. Our aim was to identify the gut microbiota associated with insulin resistance in appendix samples from morbidly obese patients classified in 2 groups, high (IR-MO) and low insulin-resistant (NIR-MO), and to determine the possible association between these gut microbiota and variables associated with insulin resistance and the expression of genes related to inflammation and macrophage infiltration in adipose tissue. Appendix samples were obtained during gastric bypass surgery and the microbiome composition was determined by 16S rRNA pyrosequencing and bioinformatics analysis by QIIME. The Chao and Shannon indices for each study group suggested similar bacterial richness and diversity in the appendix samples between both study groups. 16S rRNA pyrosequencing showed that the IR-MO group had a significant increase in the abundance ofFirmicutes,Fusobacteria,Pseudomonaceae,Prevotellaceae,Fusobacteriaceae,Pseudomonas,Catenibacterium,Prevotella,VeillonellaandFusobacteriumcompared to the NIR-MO group. Moreover, in the IR-MO group we found a significant positive correlation between the abundance ofPrevotella,Succinovibrio,FirmicutesandVeillonellaand the visceral adipose tissue expression level of IL6, TNF alpha, ILB1 and CD11b respectively, and significant negative correlations between the abundance ofButyricimonasandBifidobacterium, and plasma glucose and insulin levels, respectively. In conclusion, an appendix dysbiosis occurs in IR-MO patients, with a loss of butyrate-producing bacteria, essential to maintenance of gut integrity, together with an increase in mucin-degrading bacteria and opportunistic pathogens. The microbiota present in the IR-MO group were related to low grade inflammation in adipose tissue and could be useful for developing strategies to control the development of insulin resistance.
authors.affiliation: Clinical Management Unit of Endocrinology and Nutrition, Laboratory of The Biomedical Research Institute of Malaga (IBIMA), Virgen de la Victoria University Hospital, Malaga UniversityMalaga, Spain; Biomedical Research Networking Center for Pathophysiology of Obesity and NutritionMadrid, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Moreno-Indias
authors.affiliation: Clinical Management Unit of Endocrinology and Nutrition, Laboratory of The Biomedical Research Institute of Malaga (IBIMA), Virgen de la Victoria University Hospital, Malaga University Malaga, Spain.
authors.forename: Lidia
authors.initials: L
authors.lastname: Sánchez-Alcoholado
authors.affiliation: Biomedical Research Networking Center for Pathophysiology of Obesity and NutritionMadrid, Spain; Clinical Management Unit of Endocrinology and Nutrition, Biomedical Research Institute of Malaga (IBIMA), Regional University HospitalMalaga, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: García-Fuentes
authors.affiliation: Clinical Management Unit of Endocrinology and Nutrition, Laboratory of The Biomedical Research Institute of Malaga (IBIMA), Virgen de la Victoria University Hospital, Malaga UniversityMalaga, Spain; Biomedical Research Networking Center for Pathophysiology of Obesity and NutritionMadrid, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Cardona
authors.affiliation: Clinical Management Unit of Endocrinology and Nutrition, Laboratory of The Biomedical Research Institute of Malaga (IBIMA), Virgen de la Victoria University Hospital, Malaga UniversityMalaga, Spain; Biomedical Research Networking Center for Pathophysiology of Obesity and NutritionMadrid, Spain.
authors.forename: Maria Isabel
authors.initials: MI
authors.lastname: Queipo-Ortuño
authors.affiliation: Clinical Management Unit of Endocrinology and Nutrition, Laboratory of The Biomedical Research Institute of Malaga (IBIMA), Virgen de la Victoria University Hospital, Malaga UniversityMalaga, Spain; Biomedical Research Networking Center for Pathophysiology of Obesity and NutritionMadrid, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Tinahones
keywords: Microbiota; adipose tissue; appendix; gut integrity; inflammation; insulin resistance