Advances in Understanding the Human Gut Microbiota and Its Implication in Pediatric Celiac Disease—A Narrative Review

Celiac disease (CD) is a multifactorial disorder, defined by a complex interplay of genetic and environmental factors. Both genetic predisposition and dietary exposure to gluten are essential factors in triggering CD. However, there is proof that their presence is necessary, but not sufficient, for disease development. Through gut microbiota modulation, several additional environmental factors have shown their potential role as co-factors in CD pathogenesis. The aim of this review is to illustrate the possible mechanisms that stand behind the gut microbiota’s involvement in CD pathogenesis. Furthermore, we discuss microbiota manipulation’s potential role as both a preventative and therapeutic option. The available literature provides evidence that even before CD onset, factors including cesarean birth and formula feeding, as well as intestinal infection exposure, amplify the risk of CD in genetically predisposed individuals, due to their influence on the intestinal microbiome composition. Active CD was associated with elevated levels of several Gram-negative bacterial genera, including Bacteroides, Escherichia, and Prevotella, while beneficial bacteria such as lactobacilli and bifidobacteria were less abundant. Viral and fungal dysbiosis has also been described in CD, evidencing specific taxa alteration. A gluten-free diet (GFD) may improve the clinical symptoms and duodenal histopathology, but the persistence of intestinal dysbiosis in CD children under a GFD urges the need for additional therapy. Probiotics, prebiotics, and fecal microbial transplant have demonstrated their efficacy in restoring gut microbiota eubiosis in adult CD patients; however, their efficacy and safety as adjunctive therapies to a GFD in pediatric patients needs further investigation.