title: Effect of hypomagnesemia on allogeneic activation in mice.
abstract: BACKGROUND
  Magnesium (Mg) plays an essential role in a wide range of fundamental cellular reactions. It has been reported that in rodents Mg-deficient diet-induced hypomagnesemia results in an early inflammation. We have previously shown that chronic severe hypomagnesemia was associated neither with endothelial cell activation nor with an inflammatory process which are crucial in the allograft rejection process. T cell allogeneic stimulation activates the phosphatase calcineurin which triggers the signaling pathways leading to IL-2 synthesis and lymphocyte proliferation. Full activation of calcineurin requires Mg. Surveys suggest that a significant number of people consume less Mg than the international dietary reference intakes leading to hypomagnesemia in 2.5% to 15% of the general population.
  
  
  OBJECTIVE
  The aim of the study was to investigate the effects of hypomagnesemia on lymphocyte allogeneic activation and proliferation in a murine model of dietary-induced hypomagnesemia.
  
  
  METHODS
  C57BL/6J (H-2(b), Mls(b)) mice were given normal Mg-containing diet (1400 ppm Mg, control mice), or synthetic Mg-deficient diets containing either 50 ppm Mg or 150 ppm Mg for 28 days. Serum Mg levels were determined at days 5, 14 and 28. In parallel, complete urine and faeces were collected by using metabolic cages during a 24 h period for Mg determinations. Splenocytes from C57BL/6 mice fed either normal diet or 50 ppm Mg-diet were used as responder cells in mixed lymphocyte reaction (MLR) performed with splenocytes from C3H/He mice (H-2(k), Mls(IIa)) and C57BL/6 mice fed normal diet as stimulators for allogeneic and isogeneic conditions, respectively. TGF-beta and IL-2 productions were quantified in the supernates of mixed splenocytes cultures. 3x10(6) splenocytes from mice fed 50 ppm Mg-diet were used for calcineurin activity determination at day 28.
  
  
  RESULTS
  In mice fed 150 ppm Mg-diet, moderate hypomagnesemia was observed from day 5 to day 28. Oral supplementation with Mg pidolate (5 or 20 mg Mg/kg/day) could not restore normal serum Mg levels. Serum Mg concentration early decreased in mice fed 50 ppm Mg-diet to achieve stabilized severe hypomagnesemia at days 14 and 28. Urine Mg concentration early dramatically fell down then stabilized in mice fed Mg-deficient diets. In MLR performed at day 28 with splenocytes from mice fed 50 ppm Mg-diet, proliferation and IL-2 production in allogeneic conditions were similar to control mice. No TGF-beta production was detected in any group. Lastly, calcineurin activity measured at day 28 was significantly lower in splenocyes from mice fed 50 ppm Mg-diet than in mice fed control diet.
  
  
  CONCLUSIONS
  Mg-deficiency does not alter splenocyte allogeneic activation and proliferation and IL-2 production in vitro, although it partially inhibits calcineurin activity. We hypothesize that the remaining activity is sufficient for IL-2 gene normal activation. Alternatively, Mg-deficiency may trigger other signaling pathways leading to IL-2 production.
authors.affiliation: Centre Chirurgical Marie-Lannelongue, 92350 Le Plessis-Robinson, France.
authors.forename: Fadi
authors.initials: F
authors.lastname: Sabbagh
authors.forename: Florence
authors.initials: F
authors.lastname: Lecerf
authors.forename: Anne
authors.initials: A
authors.lastname: Hulin
authors.forename: Pierre
authors.initials: P
authors.lastname: Bac
authors.forename: Michèle
authors.initials: M
authors.lastname: German-Fattal
mesh_terms: D000818:Animals; D019703:Calcineurin / Q000276:immunology; D004032:Diet; D005260:Female; D007376:Interleukin-2 / Q000096:biosynthesis / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology*; D007959:Lymphocyte Culture Test, Mixed; D008274:Magnesium / Q000097:blood / Q000378:metabolism*; D008275:Magnesium Deficiency / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D013154:Spleen / Q000276:immunology* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000276:immunology
chemical_list: D007376:Interleukin-2; D016212:Transforming Growth Factor beta; D019703:Calcineurin; D008274:Magnesium