title: Elemental diet-induced immune suppression is caused by both bacterial and dietary factors.
abstract: Because it is unclear whether elemental diet-induced immune suppression is an indirect effect caused by the translocating bacteria or is directly caused by the elemental diet, we tested whether prevention of diet-induced bacterial translocation or disruption of the gut microflora ecology would prevent diet-induced impaired lymphocyte function in a rat elemental diet model. Prevention of diet-induced bacterial translocation was accomplished by the addition of cellulose fiber or oral antibiotics (penicillin and streptomycin) to the elemental diet feeding regimen. Control groups consisted of rat food-fed and elemental diet-fed (4.25% amino acids; 28% glucose) rats. Immune function was quantitated by measuring the mitogen-induced blastogenic response of peripheral blood or splenic mononuclear cells to the mitogens concanavalin A and phytohemagglutinin. Bacterial translocation from the gut to the mesenteric lymph node and cecal bacterial population levels were measured in all groups. Although the incidence of elemental diet-induced bacterial translocation was reduced from 100% to 25% (p < .01) by the addition of dietary fiber, fiber did not prevent diet-induced impaired lymphocyte function. Because fiber supplementation of the elemental diet did not completely prevent diet-induced intestinal bacterial overgrowth or bacterial translocation, the experiment was repeated in antibiotic-decontaminated rats. Antibiotic decontamination completely prevented diet-induced intestinal bacterial overgrowth and bacterial translocation. Although antibiotic decontamination reduced the magnitude of lymphocyte mitogen suppression (p < .05), it was not fully effective in reversing the diet-induced lymphocyte suppression. These results indicate that elemental diet-induced lymphocyte blastogenic suppression is related to both bacterial and dietary factors.
authors.affiliation: Department of Surgery, Louisiana State University Medical Center, Shreveport 71130-3932.
authors.forename: E A
authors.initials: EA
authors.lastname: Deitch
authors.forename: D
authors.initials: D
authors.lastname: Xu
authors.forename: L
authors.initials: L
authors.lastname: Qi
authors.forename: R
authors.initials: R
authors.lastname: Berg
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification*; D004043:Dietary Fiber / Q000627:therapeutic use; D005260:Female; D005526:Food, Formulated / Q000009:adverse effects*; D007165:Immunosuppression Therapy; D007422:Intestines / Q000382:microbiology*; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D008643:Mesentery / Q000382:microbiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013047:Specific Pathogen-Free Organisms; D015430:Weight Gain
chemical_list: D000900:Anti-Bacterial Agents; D004043:Dietary Fiber