title: Mast cell regulation of Na-glutamine co-transporters B0AT1 in villus and SN2 in crypt cells during chronic intestinal inflammation.
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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, 1600 Hal Greer Blvd., Huntington, WV, 25701, USA. singhs@marshall.edu.
authors.forename: Soudamani
authors.initials: S
authors.lastname: Singh
authors.affiliation: Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, 1600 Hal Greer Blvd., Huntington, WV, 25701, USA. arthursu@marshall.edu.
authors.forename: Subha
authors.initials: S
authors.lastname: Arthur
authors.affiliation: Department of Biology, LeMoyne-Owen College, Memphis, TN, 38126, USA. Jamil-Talukder@loc.edu.
authors.forename: Jamilur
authors.initials: J
authors.lastname: Talukder
authors.affiliation: Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, 1600 Hal Greer Blvd., Huntington, WV, 25701, USA. palaniappan@marshall.edu.
authors.forename: Balasubramanian
authors.initials: B
authors.lastname: Palaniappan
authors.affiliation: Boston University School of Medicine, Boston, MA, 02118, USA. coons@bu.edu.
authors.forename: Steven
authors.initials: S
authors.lastname: Coon
authors.affiliation: Department of Clinical and Translational Sciences, Joan C. Edwards School of Medicine, Marshall University, 1600 Hal Greer Blvd., Huntington, WV, 25701, USA. sundaramu@marshall.edu.
authors.forename: Uma
authors.initials: U
authors.lastname: Sundaram
mesh_terms: D026921:Amino Acid Transport Systems, Neutral / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D015550:Cell Degranulation / Q000187:drug effects*; D002908:Chronic Disease; D004751:Enteritis / Q000378:metabolism*; D020895:Enterocytes / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism*; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D007082:Ileum; D007413:Intestinal Mucosa / Q000166:cytology / Q000378:metabolism*; D007665:Ketotifen / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D008407:Mast Cells / Q000201:enzymology / Q000502:physiology*; D008871:Microvilli / Q000201:enzymology / Q000378:metabolism*; D011817:Rabbits; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: D026921:Amino Acid Transport Systems, Neutral; D006634:Histamine H1 Antagonists; C424137:SLC38A5 protein, human; D005973:Glutamine; D001619:beta-N-Acetylhexosaminidases; D000254:Sodium-Potassium-Exchanging ATPase; D007665:Ketotifen