Monocyte and M1 Macrophage-induced Barrier Defect Contributes to Chronic Intestinal Inflammation in IBD.

Background: Macrophages are key players in inflammatory bowel diseases (IBD). This study aimed to determine site-specific effects of defined macrophage subtypes on the integrity of the intestinal epithelial barrier.

Methods: Macrophage subtypes in situ in intestinal specimens of patients with IBD were visualized by immunohistochemistry.

Defective tight junctions in refractory celiac disease.

In celiac disease, the gut-associated immune system is activated in response to the ingestion of gluten, causing an atrophy of the small intestinal mucosa. Although this condition is, in most cases, responsive to a gluten-free diet, celiac disease refractory to treatment occurs in a small percentage of celiacs. An epithelial barrier defect is known to be an integral part of celiac pathophysiology.

Cell polarity-determining proteins Par-3 and PP-1 are involved in epithelial tight junction defects in coeliac disease.

Background: Epithelial barrier defects are well known in coeliac disease, but the mechanisms are only poorly defined. It is unclear, whether barrier disturbance reflects upregulated epithelial transcytosis or paracellular leakage.

Objective: To characterise the molecular structure and function of the epithelial tight junction (TJ) and mechanisms of its dysregulation.