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Background: Adhesion molecules on lymphocytes ( l -selectin and alpha4beta7) and endothelium (MAdCAM-1 and ICAM-1) direct lymphocytes into the gut-associated lymphoid tissue (GALT) of mice. Parenteral nutrition and MAdCAM-1 blockade reduce GALT cell mass. This study examined the effects on GALT cell mass of blockade of l -selectin, alpha4beta7, and ICAM-1 with saturating doses of monoclonal antibodies., Methods: In experiment 1, l -selectin and alpha4beta7 expression were measured by flow cytometry in chow-fed mice. In experiment 2, 49 mice randomly received chow, parenteral nutrition, chow + intravenous (IV) anti-CD62L, chow + IV anti-LPAM-1, or chow + IV isotype control antibody. After 4 days, lymphocyte yields in GALT and respiratory and intestinal IgA levels were measured. In experiment 3, 27 mice randomly received chow, parenteral nutrition, chow + IV anti-ICAM-1 monoclonal antibody, or chow + IV isotype control antibody for 5 days. Lymphocyte counts and IgA levels were determined as in experiment 2., Results: Some 80% of all circulating lymphocytes were positive for l -selectin and alpha4beta7. Lymphocyte counts in the Peyer's patches, lamina propria, and intraepithelial space were lower in the l -selectin and alpha4beta7 blockade groups (3.1, 1.8, and 0.9 x 10(6) and 2.1, 1.9, and 0.7 x 10(6) , respectively) than in the chow group (5.9, 3.0, and 1.7 x 10(6) ; P < .02 vs the l -selectin group and P <.001 vs the alpha4beta7 group) and similar to the levels in the parenteral group. Respiratory and intestinal IgA levels are maintained in all groups except the parenteral group ( P <.04 vs the chow group). ICAM-1 blockade did not influence cell counts or IgA levels., Conclusion: Most circulating lymphocytes have GALT homing potential. Their distribution into GALT is hindered by blockade of l -selectin or alpha4beta7, but not by ICAM-1.

Background: Parenteral nutrition (PN) decreases gut-associated lymphoid tissue (GALT), the intestinal IgA stimulating cytokines IL-4 and IL-10 in gut homogenates, intestinal IgA levels and the expression of Peyer patch (PP) mucosal cellular adhesion molecule-1 (MAdCAM-1), an adhesion molecule found on the high endothelial venules of PP and other tissues. IL-4 in PP stimulates MAdCAM expression in vitro. MAdCAM-1 blockade with MECA-367 reduces GALT cell populations to PN levels but maintains intestinal IgA levels if the animals are chow fed. This study compares IL-4 levels in PP of chow and PN fed mice and measures the effects of MAdCAM blockade on IL-4 and IL-10 levels in gut homogenates of chow fed mice. We hypothesized that in vivo IL-4 levels drop in PP of PN fed mice and IL-4 and IL-10 levels are maintained after MAdCAM-1 blockade in chow fed mice., Methods: Exp 1: 18 mice received chow or PN for 5 days to determine PP IL-4 levels. Exp 2: 44 mice were randomized to chow + control monoclonal antibody (mAb), chow + MECA-367 (anti-MAdCAM-1 mAb) or PN for 4 days before measurement of IL-4 and IL-10 levels in gut homogenates., Results: Exp 1: IL-4 levels in vivo were lower in PP of PN-fed mice than chow fed mice (92.0 +/- 15.1 pg/mL vs 251.1 +/- 14.8, p = .0003). Exp 2: IL-4 levels were significantly higher in chow + control mAb (187.1 +/- 44.1 pg/mL) and chow + MECA-367 (110.9 +/- 19.1 pg/mL) groups than PN mice (21.8 +/- 30.6 pg/mL, p < .02 vs chow + control or chow + MECA-367). IL-10 levels were significantly lower with PN (23.1 +/- 40.9 pg/mL) with chow+control (174.0 +/- 22.2 pg/mL p < .01), or chow + MECA-367 (181.7 +/- 23.1 pg/mL, p < .02 vs PN)., Conclusions: PN-feeding reduces in vivo IL-4 levels in PP (consistent with lowered MAdCAM-1 expression) and IL-4 and IL-10 levels in gut homogenates compared with chow. Despite MAdCAM-1 blockade, enteral feeding preserved gut IL-4 levels and increased IL-10 levels consistent with preserved IgA levels.

Background: Bombesin, the amphibian analog of mammalian gastrin-releasing peptide, reverses total parenteral nutrition (TPN)-induced atrophy of gut-associated lymphoid tissue and increases intestinal and respiratory immunoglobulin A (IgA) levels. Structure-activity studies suggested that the biologically active portion of bombesin is a C-terminal heptapeptide (7AA). This study investigates the effect of 7AA on lymphocytes counts of the Peyer's patches (PP), the lamina propria (LP) and the intraepithelial layer (IE)., Methods: Forty-eight male mice were randomized to receive chow (n = 13), TPN only (n = 9), TPN + 15 microg 7AA 3 times per day (n = 13) or TPN + 150 microg 7AA 3 times per day (n = 13). After 5 days of feeding, PP, LP, and IE lymphocytes were determined. Intestinal IgA levels were measured with ELISA. Groups were compared with ANOVA., Results: All TPN-fed mice lost more weight than mice fed chow (p < .04). Lymphocyte counts in PP, LP, and IE were significantly lower in the TPN group than in the 3 other groups but did not differ between the groups fed chow, TPN + 15 microg 7AA 3 times per day, or TPN + 150 microg 7AA 3 times per day. Intestinal IgA levels were higher in chow-fed mice (148.4 +/- 16.9) than in mice fed TPN (98.4 +/- 14.0, p = .008), TPN + 15 microg 7AA 3 times per day (96.9 +/- 7.7, p = .003) or TPN + 150 microg 7AA 3 times per day (87.3 +/- 6.7, p = .001)., Conclusions: The C-terminal heptapeptide of bombesin prevented the TPN-induced decrease in intestinal lymphocyte populations but not the reduction in intestinal IgA levels.

Background: Malnutrition impairs host immunity, resulting in high mortality and morbidity, secondary to infections. Nuclear factor kappaB (NFkappaB) plays a critical role in host defense, but how quickly refeeding normalizes the impaired NFkappaB activity in peritoneal resident cells (PRCs) is unknown. Our aim was to investigate the effects of 1-day ad libitum refeeding on severe diet restriction-induced NFkappaB activity in PRCs., Methods: Mice received chow, 146 g/kg per day (ad libitum) or 36.5 g/kg per day (severe diet restriction), for 7 days. One-half the mice in the diet-restricted group were then fed ad libitum for 1 day (refeeding). PRCs were harvested by peritoneal lavage. After incubation with tumor necrosis factor-alpha (TNF-alpha), nuclear translocation of NFkappaB in PRCs was investigated using laser scanning cytometry., Results: The main subpopulation of PRCs was macrophages in all groups. Mean fluorescence intensity over the nuclear area at 0 or 100 ng/mL of TNF-alpha was 16 +/- 2 or 31 +/- 8* in the ad libitum, 20 +/- 4 or 19 +/- 3 in the severe diet-restricted, and 20 +/- 4 or 30 +/- 5* in the refeeding group, respectively (*p < .05 versus 0 ng/mL of TNF-alpha in each group versus 100 ng/mL of TNF-alpha in diet-restricted group). Cytoplasmic accumulation of NFkappaB was significantly increased after TNF-alpha stimulation in the refed group but not in the ad libitum group., Conclusions: The blunted NFkappaB activity in PRCs, after exposure to inflammatory stimuli, was restored after 1 day of refeeding, with increased accumulation of NFkappaB in the cytoplasm. Even brief nutritional replenishment in malnutrition may improve host defense by restoring NFkappaB activity and thereby improving macrophage functions.

Background: Mucosal addressin cell adhesion molecule-1 (MAdCAM-1) is an adhesion molecule that directs naive T and B cells into Peyer's patches for sensitization and distribution to intestinal and extraintestinal sites. With no enteral stimulation, its expression drops rapidly in association with reduced Peyer's patch cell populations and increases rapidly with reinstitution of enteral feeding. Because both glutamine (GLN) and bombesin (BBS) preserve mucosal immunity, this study examined whether they preserve MAdCAM-1 expression., Methods: In 2 separate experiments, animals were randomized to IV cannulation with chow, total parenteral nutrition (TPN), and (experiment 1) 15 microg/kg BBS 3 times per day or (experiment 2) an isocaloric, isonitrogenous 2% GLN-supplemented solution. After 5 days of feeding, MAdCAM-1 expression in Peyer's patches, spleen, and intestine was measured using a dual radiolabeled monoclonal antibody technique., Results: MAdCAM-1 expression was not significantly improved from TPN levels either with BBS or GLN supplementation. Levels of MAdCAM-1 expression remained unchanged in non-Peyer's patch sites., Conclusions: Although MAdCAM-1 is considered the gateway molecule for cell entry into mucosal immunity, this does not seem to be the mechanism for mucosal immunity preservation in nonenterally fed mice receiving bombesin or glutamine.

Antibiotic therapy is an essential treatment for gram-negative bacterial infections. Antibiotic-induced endotoxin release and subsequent production of inflammatory cytokines reportedly depend on the type of antibiotic action. This study examined the effects of various beta-lactam antibiotics on cell death of human polymorphonuclear neutrophils (PMNs) cocultured with Escherichia coli (E. coli) in vitro. E. coli morphology after antibiotic treatment was determined. PMNs and E. coli were cocultured with antibiotics for 0, 4, or 12 h. Levels of endotoxin and cytokines (TNF-alpha, IL-1beta, and IL-6) in the supernatants were measured. The filtrates of antibiotic-treated E. coli supernatants were cocultured with PMNs for 0, 4, or 12 h. In all experiments, ampicillin (ABPC), cefazolin sodium (CEZ), cefoperazone sodium (CPZ), latamoxef sodium (LMOX), imipenem (IPM), and polymyxin B sulfate (PLB) were used at 30 microg/mL. PMNs were isolated from healthy volunteers. PMN cell death was assessed by flow cytometry and light microscopy. ABPC, CEZ, CPZ, and LMOX, which induce bacterial filament formation with lysis, caused PMN necrosis when cocultured with E. coli. In contrast, IPM, which induces bacterial spheroplast formation with lysis, caused PMN apoptosis. Levels of endotoxin, TNF-alpha and IL-6 in the supernatants with IPM and PLB were significantly lower than in those with other beta-lactam antibiotics. The filtrates of IPM- and PLB-treated E. coli supernatants induced PMN apoptosis, whereas those treated with other beta-lactam antibiotics increased PMN necrosis. Beta-lactam antibiotics have different impacts on the types of PMN cell death after E. coli killing. Underlying mechanisms and the clinical relevance of IPM-induced PMN apoptosis in severe gram-negative infection warrant further investigation.

Background: Total parenteral nutrition (TPN) alters gut cytokines and mucosal immunity and increases intercellular adhesion molecule-1 (ICAM-1) expression, gut neutrophil levels, and mortality after gut ischemia. Supplementation of TPN with glutamine partially supports mucosal immunity by preserving respiratory and intestinal IgA levels, maintaining the proper IgA-stimulating cytokine milieu within the intestine, and reducing intestinal ICAM-1 expression and neutrophil accumulation. This work investigates whether glutamine supplementation of TPN affects mortality in mice after gut ischemic insult., Methods: Thirty-eight mice were randomized to receive chow, TPN, or 2% glutamine-supplemented TPN (GLN-TPN) for 5 days. After feeding their respective diets, gut ischemia/reperfusion (I/R) was induced with superior mesenteric artery occlusion for 30 minutes followed by resuscitation with 1 mL saline. Survival was recorded until 72 hours after reperfusion., Results: Survival time was significantly reduced in the TPN-fed mice compared with both chow-fed and GLN-TPN-fed mice (p < .05). Survival at 72 hours after reperfusion was also significantly lower in the TPN-fed mice than in the chow-fed and GLN-TPN-fed mice (p < .05), Conclusions: Glutamine supplementation of TPN significantly improves survival after gut I/R, suggesting modulation of the inflammatory response or improved gut tolerance to low-flow states.