Background Intestinal epithelial barrier dysfunction (“leaky gut
syndrome”, LGS) is thought to play a major role in the pathogenesis of disorders of the gut
brain axis. Endoscopic confocal laser endomicroscopy (eCLE) is an objective measure to test
duodenal permeability. We applied this technique in patients with functional gastrointestinal
symptoms and food intolerance to characterize the proportion of patients with LGS.
Material and Methods In an observational study, we evaluated 85
patients with functional gastrointestinal symptoms and food intolerance. Gastrointestinal
symptoms were classified according to Rom IV into functional abdominal pain (FAP), irritable
bowel syndrome (IBS), irritable bowel syndrome diarrhea dominant (IBS-D), irritable bowel
syndrome constipation dominant (IBS-C), irritable bowel syndrome with mixed stool (IBS-M),
functional abdominal bloating (FAB), functional diarrhea (FD) and unclassified (NC). During
eCLE, spontaneous transfer of intravenously applied fluorescein into duodenal lumen (LGS) and
following duodenal food challenge (DFC) were analyzed. Blood analysis comprised parameters of mast cell
function, histology of duodenal mucosal biopsies analysis of mucosal inflammation,
intraepithelial lymphocytes (IELs) as well as number, distribution and morphology of mast
cells.
Results 24 patients (9 IBS, 9 FAP, 3 FAB, 1 FD, 2 NC), showed
LGS, 50 patients (14 IBS-D, 4 IBS-C, 3 IBS-M, 23 FAP, 3 FAB, 3 NC) had no LGS but responded to
DFC and 11 patients (6 NC, 3 FAP, 1 FAB, 1 FD) had no LGS and no response to DFC. The
proportion of subgroups with/or without spontaneous leakage of fluorescein (+LGS/-LGS) were
IBS-LGS/IBS+LGS 67%/33%, FAP-LGS/FAP+LGS 72%/28%,FAB-LGS/FAB+LGS 50%/50%, NC-LGS/NC+LGS
60%/40%. Subgroup analysis revealed no significant differences for all parameters
tested.
Conclusion As a proof of concept, the results of our study
indicate that eCLE is a clinical useful tool to evaluate patients with disorders of the gut
brain axis and those suspicious of LGS. However, the clinical significance of LGS remains
unclear. The study should be an incentive to perform a randomized study including healthy
controls.