Coeliac disease is a chronic intestinal inflammatory disorder due to an aberrant immune response to dietary gluten proteins in genetically predisposed individuals. Mucosal immune response through IgA secretion constitutes a first line of defence responsible for neutralizing noxious antigens and pathogens. The aim of this study was the characterization of the relationships between immunoglobulin-coated bacteria and bacterial composition of faeces of coeliac disease (CD) patients, untreated and treated with a gluten-free diet (GFD) and healthy controls.
IgA-coated faecal bacterial levels were significantly lower in both untreated and treated CD patients than in healthy controls. IgG and IgM-coated bacterial levels were also significantly lower in treated CD patients than in untreated CD patients and controls. Gram-positive to Gram-negative bacteria ratio was significantly reduced in both CD patients compared to controls.
Bifidobacterium, Clostridium histolyticum, C. lituseburenseand Faecalibacterium prausnitziigroup proportions were less abundant ( P< 0.050) in untreated CD patients than in healthy controls. Bacteroides-Prevotellagroup proportions were more abundant ( P< 0.050) in untreated CD patients than in controls. Levels of IgA coating the Bacteroides-Prevotellagroup were significantly reduced ( P< 0.050) in both CD patients in comparison with healthy controls. Conclusions
In CD patients, reduced IgA-coated bacteria is associated with intestinal dysbiosis, which altogether provide new insights into the possible relationships between the gut microbiota and the host defences in this disorder.