The role of the intestinal microbiota in the pathogenesis of chronic enteropathies and their interplay with the immune system

Abstract

The intestinal microbiota and its associated genome is collectively called the gastrointestinal (GI) microbiome, and is composed of crucial components that help not only to determine host biology but also to maintain host physiology. Dysregulation of the gastrointestinal microbiome has been associated with a range of diseases in people such as inflammatory bowel disease (IBD), diabetes and obesity. Previous studies have found dysbiosis and a reduced bacterial diversity in dogs with chronic enteropathies (CE). However, the precise nature of the intestinal microbiota dysfunction and whether the microbiota has a causative role or is secondarily affected remain to be elucidated.

The first step in understanding the relationship between the gut microbiota and disease is the characterisation of the normal gut microbiota, how it is established and how stable it is during different periods of life. In this work, we assessed the dynamics and stability of faecal microbiota over time in healthy dogs of different age groups, and the development of the microbiota from birth in puppies, and the association with the maternal microbiome. Next, we characterised highly immunoglobulin A and G coated bacteria in faecal samples from dogs with chronic enteropathies using flow cytometry and 16S rRNA sequencing and assessed their correlation with disease stage and resolution of the clinical signs. Finally, we characterised the expression of thymic stromal lymphopoetin (TSLP), a cytokine that is produced in response to bacterial contact, in the intestine of healthy dogs and its correlation with disease activity in dogs with chronic enteropathies.

The results reported here, help to understand the assembly of the gut microbiota, its interaction with the immune system and emphasise on the importance of longitudinal studies and personalised approach in order to understand the pathogenesis and the role of the microbiota in intestinal diseases in dogs.