Towards a functional hypothesis relating anti-islet cell autoimmunity to the dietary impact on microbial communities and butyrate production.
BACKGROUND
The development of anti-islet cell autoimmunity precedes clinical type 1 diabetes and occurs very early in life. During this early period, dietary factors strongly impact on the composition of the gut microbiome. At the same time, the gut microbiome plays a central role in the development of the infant immune system. A functional model of the association between diet, microbial communities, and the development of anti-islet cell autoimmunity can provide important new insights regarding the role of the gut microbiome in the pathogenesis of type 1 diabetes.


RESULTS
A novel approach was developed to enable the analysis of the microbiome on an aggregation level between a single microbial taxon and classical ecological measures analyzing the whole microbial population. Microbial co-occurrence networks were estimated at age 6 months to identify candidates for functional microbial communities prior to islet autoantibody development. Stratification of children based on these communities revealed functional associations between diet, gut microbiome, and islet autoantibody development. Two communities were strongly associated with breast-feeding and solid food introduction, respectively. The third community revealed a subgroup of children that was dominated by Bacteroides abundances compared to two subgroups with low Bacteroides and increased Akkermansia abundances. The Bacteroides-dominated subgroup was characterized by early introduction of non-milk diet, increased risk for early autoantibody development, and by lower abundances of genes for the production of butyrate via co-fermentation of acetate. By combining our results with information from the literature, we provide a refined functional hypothesis for a protective role of butyrate in the pathogenesis of type 1 diabetes.


CONCLUSIONS
Based on functional traits of microbial communities estimated from co-occurrence networks, we provide evidence that alterations in the composition of mucin degrading bacteria associate with early development of anti-islet cell autoimmunity. We hypothesize that lower levels of Bacteroides in favor of increased levels of Akkermansia lead to a competitive advantage of acetogens compared to sulfate reducing bacteria, resulting in increased butyrate production via co-fermentation of acetate. This hypothesis suggests that butyrate has a protective effect on the development of anti-islet cell autoantibodies.
Scientific Computing Research Unit, Helmholtz Zentrum München, Munich, Germany.
David
D
Endesfelder
Scientific Computing Research Unit, Helmholtz Zentrum München, Munich, Germany.
Marion
M
Engel
Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Munich, USA.
Austin G
AG
Davis-Richardson
Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Munich, USA.
Alexandria N
AN
Ardissone
Institute of Diabetes Research, Helmholtz Zentrum München, and Forschergruppe Diabetes, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
Peter
P
Achenbach
Institute of Diabetes Research, Helmholtz Zentrum München, and Forschergruppe Diabetes, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
Sandra
S
Hummel
Institute of Diabetes Research, Helmholtz Zentrum München, and Forschergruppe Diabetes, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
Christiane
C
Winkler
Department of Pediatrics, University of Florida, Gainesville, FL, USA.
Mark
M
Atkinson
Department of Pediatrics, University of Florida, Gainesville, FL, USA.
Desmond
D
Schatz
Department of Microbiology and Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Munich, USA.
Eric
E
Triplett
Institute of Diabetes Research, Helmholtz Zentrum München, and Forschergruppe Diabetes, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
Anette-Gabriele
AG
Ziegler
Scientific Computing Research Unit, Helmholtz Zentrum München, Munich, Germany. castell@helmholtz-muenchen.de.|Department of Mathematics, Technische Universität München, Munich, Germany. castell@helmholtz-muenchen.de.
Wolfgang
W
zu Castell
D019342:Acetic Acid / Q000276:immunology / Q000378:metabolism; D000328:Adult; D001323:Autoantibodies / Q000096:biosynthesis; D015551:Autoimmunity; D001439:Bacteroides / Q000276:immunology / Q000378:metabolism*; D001942:Breast Feeding; D020148:Butyric Acid / Q000276:immunology / Q000378:metabolism*; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D004032:Diet; D005260:Female; D005285:Fermentation; D000069196:Gastrointestinal Microbiome / Q000276:immunology*; D041981:Gastrointestinal Tract / Q000276:immunology / Q000382:microbiology*; D006801:Humans; D007113:Immunity, Innate; D007223:Infant; D007515:Islets of Langerhans / Q000276:immunology; D008297:Male; D061327:Verrucomicrobia / Q000276:immunology / Q000378:metabolism*
D001323:Autoantibodies; D020148:Butyric Acid; D019342:Acetic Acid
Butyrate; Gut microbiome; Interaction networks; Islet immunity; Mucin degradation; Type 1 diabetes