Abstract
BackgroundIrritable bowel syndrome (IBS) is a disorder with multifactorial pathophysiology. Intestinal barrier may be altered, especially in diarrhea-predominant IBS (IBS-D). Several mediators may contribute to increased intestinal permeability in IBS.AimWe aimed to assess effects of tryptase and LPS on in vitro permeability using a 3-dimensional cell model after basolateral cell exposure. Furthermore, we assessed the extent to which these mediators in IBS plasma play a role in intestinal barrier function.Materials and MethodsCaco-2 cells were grown in extracellular matrix to develop into polarized spheroids and were exposed to tryptase (10 - 50 mU), LPS (1 - 50 ng/mL) and two-fold diluted plasma samples of 7 patients with IBS-D, 7 with constipation-predominant IBS (IBS-C) and 7 healthy controls (HC). Barrier function was assessed by the flux of FITC-dextran (FD4) using live cell imaging. Furthermore, plasma tryptase and LPS were determined.ResultsTryptase (20 and 50 mU) and LPS (6.25 – 50 ng/mL) significantly increased Caco-2 permeability versus control (all P< 0.05). Plasma of IBS-D only showed significantly elevated median tryptase concentrations (7.1 [3.9 – 11.0] vs. 4.2 [2.2 – 7.0] vs. 4.2 [2.5 – 5.9] μg/mL; P<0.05) and LPS concentrations (3.65 [3.00 – 6.10] vs. 3.10 [2.60-3.80] vs. 2.65 [2.40 – 3.40] EU/ml; P< 0.05) vs. IBS-C and HC. Also, plasma of IBS-D increased Caco-2 permeability versus HC (0.14450 ± 0.00472 vs. 0.00021 ± 0.00003; P < 0.001), which was attenuated by selective inhibition of tryptase and LPS (P< 0.05).ConclusionBasolateral exposure of spheroids to plasma of IBS-D patients resulted in a significantly increased FD4 permeation, which was partially abolished by selective inhibition of tryptase and LPS. These findings point to a role of systemic tryptase and LPS in the epithelial barrier alterations observed in patients with IBS-D.
Highlights
Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder, with an estimated prevalence of 10–15% in Western countries [1]
Plasma of IBS-D increased Caco-2 permeability versus healthy controls (HC) (0.14450 ± 0.00472 vs. 0.00021 ± 0.00003; P < 0.001), which was attenuated by selective inhibition of tryptase and LPS (P< 0.05)
Basolateral exposure of spheroids to plasma of IBS-D patients resulted in a significantly increased fluorescein isothiocyanate-labelled dextran of 4 kDa (FD4) permeation, which was partially abolished by selective inhibition of tryptase and LPS
Summary
Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder, with an estimated prevalence of 10–15% in Western countries [1]. It is characterized by chronic abdominal pain or discomfort, and altered bowel habits in the absence of an organic cause [2]. Alterations in the intestinal barrier have been reported in patients with IBS [9, 10] and were found to be associated with GI symptoms, such as diarrhea and abdominal pain [5]. It has been hypothesized that barrier dysfunction is an early event in IBS and may contribute to low-grade intestinal inflammation and increased visceral perception [11].
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