Celiac Disease and Autoimmunity - The Missing Ingredient

Dietary Gluten as a Conditioning Factor of the Gut Microbiota in Celiac Disease

The gut microbiota plays a relevant role in determining an individual's health status, and the diet is a major factor in modulating the composition and function of gut microbiota. Gluten constitutes an essential dietary component in Western societies and is the environmental trigger of celiac disease. The presence/absence of gluten in the diet can change the diversity and proportions of the microbial communities constituting the gut microbiota. There is an intimate relation between gluten metabolism and celiac disease pathophysiology and gut microbiota; their interrelation defines intestinal health and homeostasis. Environmental factors modify the intestinal microbiota and, in turn, its changes modulate the mucosal and immune responses. Current evidence from studies of young and adult patients with celiac disease increasingly supports that dysbiosis (i.e., compositional and functional alterations of the gut microbiome) is present in celiac disease, but to what extent this is a cause or consequence of the disease and whether the different intestinal diseases (celiac disease, ulcerative colitis, Crohn disease) have specific change patterns is not yet clear. The use of bacterial-origin enzymes that help completion of gluten digestion is of interest because of the potential application as coadjuvant in the current treatment of celiac disease. In this narrative review, we address the current knowledge on the complex interaction between gluten digestion and metabolism, celiac disease, and the intestinal microbiota.

Celiac Disease Prevalence is Increased in Primary Sjögren's Syndrome and Diffuse Systemic Sclerosis: Lessons from a Large Multi-Center Study

Association of celiac disease (CD) with systemic autoimmune diseases (ADs) remains controversial. Awareness of CD in these patients is important to prevent complications, including lymphoproliferative disorders. We evaluated previously diagnosed CD prevalence in systemic lupus erythematosus (SLE), primary Sjögren’s syndrome (pSS) and systemic sclerosis (SSc) patients in comparison to 14,298 matched controls. All patients were screened for subclinical CD. Data from 1458 unselected consecutive SLE (580), pSS (354) and SSc (524) patients were collected. Previously biopsy-proven CD diagnosis and both CD- and AD-specific features were registered. All patients without previous CD were tested for IgA transglutaminase (TG). Anti-endomysium were tested in positive/borderline IgA TG. Duodenal biopsy was performed in IgA TG/endomysium+ to confirm CD. CD prevalence in AD was compared to that observed in 14,298 unselected sex- and age-matched adults who acted as controls. CD was more prevalent in pSS vs controls (6.78% vs 0.64%, p < 0.0001). A trend towards higher prevalence was observed in SLE (1.38%, p = 0.058) and SSc (1.34%, p = 0.096). Higher CD prevalence was observed in diffuse cutaneous SSc (4.5%, p ≤ 0.002 vs controls). Subclinical CD was found in two SLE patients and one pSS patient. CD diagnosis usually preceded that of AD. Primary SS and SSc–CD patients were younger at AD diagnosis in comparison to non-celiac patients. Autoimmune thyroiditis was associated with pSS and CD. CD prevalence is clearly increased in pSS and diffuse SSc in comparison to the general population. The association of CD with diffuse but not limited SSc may suggest different immunopathogenic mechanisms characterizing the two subsets. CD screening may be considered in pSS and diffuse SSc in young patients, particularly at the time of diagnosis.