Acute Effects of Butyrate on Induced Hyperpermeability and Tight Junction Protein Expression in Human Colonic Tissues

Abstract

Intact intestinal barrier function is essential for maintaining intestinal homeostasis. A dysfunctional intestinal barrier can lead to local and systemic inflammation through translocation of luminal antigens and has been associated with a range of health disorders. Butyrate, a short-chain fatty acid derived from microbial fermentation of dietary fibers in the colon, has been described as an intestinal barrier-strengthening agent, although mainly by using in vitro and animal models. This study aimed to investigate butyrate's ability to prevent intestinal hyperpermeability, induced by the mast cell degranulator Compound 48/80 (C48/80), in human colonic tissues. Colonic biopsies were collected from 16 healthy subjects and intestinal permeability was assessed by Ussing chamber experiments. Furthermore, the expression levels of tight junction-related proteins were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Pre-treatment with 5 mM butyrate or 25 mM butyrate did not protect the colonic tissue against induced paracellular or transcellular hyperpermeability, measured by FITC-dextran and horseradish peroxidase passage, respectively. Biopsies treated with 25 mM butyrate prior to stimulation with C48/80 showed a reduced expression of claudin 1. In conclusion, this translational ex vivo study did not demonstrate an acute protective effect of butyrate against a chemical insult to the intestinal barrier in healthy humans.

Keywords: Ussing chamber; butyrate; intestinal barrier function; intestinal permeability; tight junctions.

Figure 1

Median baseline TER (MTER) for the different treatment groups. Boxplots show MTER with the marked median, and whiskers visualize minimum and maximum values. MTER was determined within a time period of 10 min (T-30 to T-20) prior to any treatment or stimulation of colonic biopsies mounted in Ussing chambers. n = 10.

Figure 2

Effects of butyrate on intestinal permeability in colonic biopsies mounted in Ussing chambers. Paracellular permeability (A) and transcellular permeability (B) are displayed with dots connected by a line for each participant. Biopsies were analyzed in biological triplicates with no stimulation, stimulation with C48/80 (10 ng/mL) alone or in combination with 5 mM sodium butyrate or 25 mM sodium butyrate, respectively. * p < 0.05, n = 10.

Figure 3

Gene expression levels of tight junction proteins and NF–κB inhibitor alpha (IkB–alpha). Boxplots show logarithmic fold changes of unstimulated or C48/80 plus butyrate-treated vs. C48/80–stimulated biopsies alone. Median values are indicated, and whiskers visualize minimum and maximum values. ** p < 0.01, n = 9.