Mast cell regulation of Na-glutamine co-transporters B0AT1 in villus and SN2 in crypt cells during chronic intestinal inflammation

BMC Gastroenterol. 2015 Apr 15;15:47. doi: 10.1186/s12876-015-0275-5.

Abstract

Background: In the chronically inflamed rabbit small intestine, brush border membrane (BBM) Na-glutamine co-transport is inhibited in villus cells (mediated by B0AT1), while it is stimulated in crypt cells (mediated by SN2/SNAT5). How mast cells, known to be enhanced in the chronically inflamed intestine, may regulate B0AT1 in villus and SN2/SNAT5 in crypt cell is unknown. Thus, the aim of the present study is to determine the regulation of B0AT1 and SN2/SNAT5 by mast cells during chronic enteritis.

Methods: Chronic intestinal inflammation was induced in male rabbits with intra-gastric inoculation of Eimeria magna oocytes. Rabbits with chronic inflammation were treated with ketotifen (10 mg/day) or saline (Placebo) for 2 days. Villus and crypts cells were isolated from the rabbit intestine using the Ca++ chelation technique. Na/K-ATPase activity was measured as Pi from cellular homogenate. BBM vesicles (BBMV) were prepared from villus and crypt cells and uptake studies were performed using rapid filtration technique with (3)H-Glutamine. Western blot analyses were done using B0AT1 and SN2 specific antibodies.

Results: In villus cells, Na-glutamine co-transport inhibition observed during inflammation was completely reversed by ketotifen, a mast cell stabilizer. In contrast, in crypt cells, Na-glutamine co-transport stimulation was reversed to normal levels by ketotifen. Kinetic studies demonstrated that ketotifen reversed the inhibition of B0AT1 in villus cells by restoring co-transporter numbers in the BBM, whereas the stimulation of SN2/SNAT5 in crypts cells was reversed secondary to restoration of affinity of the co-transporter. Western blot analysis showed that ketotifen restored immune-reactive levels of B0AT1 in villus cells, while SN2/SNAT5 levels from crypts cell remained unchanged.

Conclusion: In the present study we demonstrate that mast cells likely function as a common upstream immune pathway regulator of the Na-dependent glutamine co-transporters, B0AT1 in villus cells and SN2 in crypts cells that are uniquely altered in the chronically inflamed small intestine.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Transport Systems, Neutral / metabolism*
  • Animals
  • Biological Transport / drug effects
  • Cell Degranulation / drug effects*
  • Chronic Disease
  • Enteritis / metabolism*
  • Enterocytes / metabolism
  • Glutamine / metabolism*
  • Histamine H1 Antagonists / pharmacology
  • Ileum
  • Intestinal Mucosa / cytology
  • Intestinal Mucosa / metabolism*
  • Ketotifen / pharmacology
  • Kinetics
  • Male
  • Mast Cells / enzymology
  • Mast Cells / physiology*
  • Microvilli / enzymology
  • Microvilli / metabolism*
  • Rabbits
  • Sodium-Potassium-Exchanging ATPase / metabolism
  • beta-N-Acetylhexosaminidases / metabolism

Substances

  • Amino Acid Transport Systems, Neutral
  • Histamine H1 Antagonists
  • SLC38A5 protein, human
  • Glutamine
  • beta-N-Acetylhexosaminidases
  • Sodium-Potassium-Exchanging ATPase
  • Ketotifen