title: Bacterial infection affects protein synthesis in primary lymphoid tissues and circulating lymphocytes of rats.
abstract: Bacterial infection alters whole-body protein homeostasis. Although immune cells are of prime importance for host defense, the effect of sepsis on their protein synthesis rates is poorly documented. We analyzed protein synthesis rates in rat primary lymphoid tissues and circulating lymphocytes after infection. Male Sprague-Dawley rats were studied 1, 2, 6 or 10 d after an intravenous injection of live Escherichia coli. Control healthy rats consumed food ad libitum (d 0) or were pair-fed to infected rats. Protein synthesis was quantified using a flooding dose of L-(4,4,4-(2)H(3))valine. Sepsis induced a delayed increase in total blood leukocytes and a rapid and persistent inversion of the counts. Basal fractional rates of protein synthesis (ks) were 117, 73 and 29%/d in bone marrow, thymus and circulating lymphocytes, respectively. Pair-feeding strongly depressed the absolute protein synthesis rates (ASR) of bone marrow (d 2 and 10) and thymus (d 2-10). The infection per se increased bone marrow, thymus and circulating lymphocyte ks but at various postinfection times. It decreased bone marrow (d 1) and thymus (d 1 and 2) ASR but increased lymphocyte (d 2 and 10) and bone marrow (d 10) ASR. Our results reflect the deleterious effect of anorexia on primary lymphoid tissues. The host defense against bacterial infection exhibited time- and tissue-dependent modifications of protein synthesis, indicating that blood lymphocyte protein data are not representative of the immune system as a whole. Optimization of nutritional supports would be facilitated by including protein synthesis measurements of the immune system.
authors.affiliation: Unité de Nutrition et Métabolisme Protéique, INRA Theix, 63122 Saint-Genès-Champanelle, France. papet@clermont.inra.fr
authors.forename: Isabelle
authors.initials: I
authors.lastname: Papet
authors.forename: Benoît
authors.initials: B
authors.lastname: Ruot
authors.forename: Denis
authors.initials: D
authors.lastname: Breuillé
authors.forename: Stéphane
authors.initials: S
authors.lastname: Walrand
authors.forename: Marie-Chantal
authors.initials: MC
authors.lastname: Farges
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Vasson
authors.forename: Christiane
authors.initials: C
authors.lastname: Obled
mesh_terms: D000818:Animals; D001853:Bone Marrow / Q000378:metabolism; D004927:Escherichia coli Infections / Q000097:blood / Q000378:metabolism*; D007958:Leukocyte Count; D008214:Lymphocytes / Q000378:metabolism*; D008221:Lymphoid Tissue / Q000378:metabolism*; D008297:Male; D014176:Protein Biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013950:Thymus Gland / Q000378:metabolism