Abnormal Uroguanylin Immunoreactive Cells Density in the Duodenum of Patients with Diarrhea-Predominant Irritable Bowel Syndrome Changes following Fecal Microbiota Transplantation

Abstract

Altered densities of enteroendocrine cells play an important role in patients with irritable bowel syndrome (IBS). Uroguanylin activates guanylate cyclase-C to regulate intestinal electrolyte and water transport. Aim. To quantify uroguanylin immunoreactive cells density in the duodenum of diarrhea-predominant IBS (IBS-D) patients compared to controls and to investigate the effect of fecal microbiota transplantation (FMT) on these cell densities. Method. Twelve patients with IBS-D according to Rome III criteria were included. The cause was identified as post infectious (PI, n = 6) or idiopathic (n = 6). They completed the IBS-symptom questionnaire before and 3 weeks after FMT. Thirty grams of fresh feces donated from healthy relatives were diluted with 60 ml normal saline and instilled via endoscope into the duodenum. Biopsies were taken from the patients' duodenum before and 3 weeks after FMT. Duodenal biopsies taken from eight healthy controls were also included. The biopsies were immunostained for uroguanylin and quantified using computerized image analysis. Results. Uroguanylin immunoreactive cells were found both in duodenal villi and crypts in both controls and IBS-D patients. The densities of uroguanylin immunoreactive cells were significantly lower in the villi (P < 0.0001) and higher in the crypts (P < 0.0001) for the patients than the controls. Following FMT, the densities of uroguanylin immunoreactive cells for the total group and idiopathic subgroup decreased significantly in the duodenal crypts (P = 0.049 and 0.04, respectively) but not in the villi. No significant changes were shown in the PI-IBS subgroups. The cells density in only the crypts correlated with diarrhea (r = 0.97, P = 0.001) and bloating (r = -0.91, P = 0.01) in the PI-IBS subgroup before FMT and with abdominal pain (r = 0.63, P = 0.03) in the total group of IBS-D patients after FMT. Conclusion. Altered uroguanylin immunoreactive cells density was found in IBS-D patients compared to controls. Changes in these cells density following FMT correlated with IBS symptoms (diarrhea, bloating, and abdominal pain).

Figure 1

Activation cascade of binding of uroguanylin to guanylate cyclase-C receptor on the intestinal epithelial cell. Binding of uroguanylin to guanylate cyclase-C results in receptor activation, catalyzing the production of cyclic guanosine monophosphate (cGMP). Cyclic GMP can activate cGMP-dependent protein kinase II (PKGII) or inhibit the activity of a cyclic adenosine monophosphate- (cAMP-) specific phosphodiesterase, PDE III, thereby crossactivating cAMP-dependent protein kinase (PKA). PKGII and PKA phosphorylate the cystic fibrosis transmembrane conductance regulator or CFTR, increasing its chloride-secreting activity and preventing the absorption of sodium [37].

Figure 2

Uroguanylin immunoreactive cells in the duodenal villi for patients with irritable bowel syndrome before (a) and after (b) fecal microbiota transplantation and controls (c).

Figure 3

Uroguanylin immunoreactive cells in the duodenal crypts for patients with irritable bowel syndrome before (a) and after (b) fecal microbiota transplantation and controls (c).

Figure 4

Uroguanylin immunoreactive cells densities in the duodenal (a) villi and (b) crypts, for patients with irritable bowel syndrome and controls.

Figure 5

Correlations between scores of irritable bowel syndrome-symptom questionnaire (IBS-SQ) for (a) diarrhea, (b) bloating, and (c) abdominal pain, and uroguanylin (UGN) immunoreactive cells density of the crypt in post infectious (PI-IBS) and total group of patients with irritable bowel syndrome before and after fecal microbiota transplantation (FMT).