Fecal and Circulating Biomarkers for the Non-Invasive Assessment of Intestinal Permeability.

The study of intestinal permeability is gaining growing interest due to its relevance in the onset and progression of several gastrointestinal and non-gastrointestinal diseases. Though the involvement of impaired intestinal permeability in the pathophysiology of such diseases is recognized, there is currently a need to identify non-invasive biomarkers or tools that are able to accurately detect alterations in intestinal barrier integrity. On the one hand, promising results have been reported for novel in vivo methods based on paracellular probes, i.e., methods that can directly assess paracellular permeability and, on the other hand, on fecal and circulating biomarkers able to indirectly assess epithelial barrier integrity and functionality. In this review, we aimed to summarize the current knowledge on the intestinal barrier and epithelial transport pathways and to provide an overview of the methods already available or currently under investigation for the measurement of intestinal permeability.

Non-invasive methods for the assessment of hepatic fibrosis: transient elastography, hyaluronic acid, 13C-aminopyrine breath test and cytokeratin 18 fragment.

BACKGROUND. In the management of chronic hepatitis C (CHC) patients, liver biopsy is the gold standard for liver fibrosis assessment despite some technical limits and risks. Non-invasive approaches have been proposed as alternative methods to evaluate structural liver damage. AIM. To investigate the diagnostic accuracy of transient elastography, 13C-aminopyrine breath test (13C-ABT), serum hyaluronic acid (HA) and cytokeratin 18 Asp396 fragment (CK-18) as non-invasive methods of liver fibrosis assessment ad their correlation to METAVIR score. MATERIAL AND METHODS. In a cohort of 57 CHC patients, liver stiffness, cumulative percentage of administered dose of 13C-aminopyrine at 120 min, serum HA and serum CK-18 concentration were determined. Diagnostic accuracy in detecting significant fibrosis (F ≥ 2), severe fibrosis (F ≥ 3) and cirrhosis (F = 4) was assessed by the area under the receiver operating characteristic curve. RESULTS. Liver fibrosis score showed a strong correlation with liver stiffness (r = 0.667; p < 0.0001) and a significant inverse correlation with 13C-ABT results (r = -0.418; p = 0.0012). A weaker correlation was found with CK18 (r = 0.329; p = 0.0126) and no correlation with HA. Areas under the curve of elastography, 13C-ABT, HA and CK18 were: 0.98, 0.75, 0.69, 0.64, respectively, for F ≥ 2; 0.97, 0.69, 0.80, 0.66, respectively, for F ≥ 3; 0.95, 0.64, 0.70, 0.56, respectively, for F = 4. CONCLUSION. Elastography has the best diagnostic accuracy for the assessment of the degree of liver fibrosis in CHC patients. Its application can provide an alternative useful tool for monitoring the disease evolution.