Intravenous Glutamine Administration Reduces Lung and Distal Organ Injury in Malnourished Rats With Sepsis

Combination of Glutamine and Ulinastatin Treatments Greatly Improves Sepsis Outcomes

Background

Sepsis is one of the most dangerous syndromes, has extremely high mortality, and is caused by the body’s extreme responses to an infection. The pathogenesis of sepsis is very complex and remains largely unknown and thus the treatments for sepsis are limited. Here, we evaluated the treatment results of two potential drugs, glutamine and ulinastatin, on sepsis.

Methods

CLP rat model was used to study sepsis. Gastrostomy was performed to deliver the drugs. Flow cytometry was employed to measure CD4 and CD8 levels. May–Grünwald–Giemsa staining was used to count the numbers of monocytes and neutrophils in the blood. ELISA assay was performed to assess the levels of PCT, IL-6, TNFα, and IL-1β.

Results

Sepsis was successfully induced with the standard CLP rat model. Both glutamine and ulinastatin treatments greatly improved the outcomes of sepsis, but the combination of both treatments had the maximum therapeutic effect. Mechanistically, PCT, IL-6, TNFα, and IL-1β levels were significantly diminished following glutamine and ulinastatin treatments, suggesting an inhibition of inflammatory responses. Further, CD4 and CD4/CD8 ratio, and the numbers of monocytes and neutrophils were greatly up-regulated by glutamine and ulinastatin, indicating an enhanced immunity.

Conclusion

Glutamine and ulinastatin treatments largely mitigate sepsis shock by suppressing the inflammatory responses of the body and strengthening the immune system. Combination of these two drugs could serve as a potential treatment for sepsis.

Mesenchymal Stem Cells From Bone Marrow, Adipose Tissue, and Lung Tissue Differentially Mitigate Lung and Distal Organ Damage in Experimental Acute Respiratory Distress Syndrome

OBJECTIVES

Mesenchymal stem cells-based therapies have shown promising effects in experimental acute respiratory distress syndrome. Different mesenchymal stem cells sources may result in diverse effects in respiratory diseases; however, there is no information regarding the best source of mesenchymal stem cells to treat pulmonary acute respiratory distress syndrome. We tested the hypothesis that mesenchymal stem cells derived from bone marrow, adipose tissue, and lung tissue would lead to different beneficial effects on lung and distal organ damage in experimental pulmonary acute respiratory distress syndrome.

DESIGN

Animal study and primary cell culture.

SETTING

Laboratory investigation.

SUBJECTS

Seventy-five Wistar rats.

INTERVENTIONS

Wistar rats received saline (control) or Escherichia coli lipopolysaccharide (acute respiratory distress syndrome) intratracheally. On day 2, acute respiratory distress syndrome animals were further randomized to receive saline or bone marrow, adipose tissue, or lung tissue mesenchymal stem cells (1 × 10 cells) IV. Lung mechanics, histology, and protein levels of inflammatory mediators and growth factors were analyzed 5 days after mesenchymal stem cells administration. RAW 264.7 cells (a macrophage cell line) were incubated with lipopolysaccharide followed by coculture or not with bone marrow, adipose tissue, and lung tissue mesenchymal stem cells (10 cells/mL medium).

MEASUREMENTS AND MAIN RESULTS

Regardless of mesenchymal stem cells source, cells administration improved lung function and reduced alveolar collapse, tissue cellularity, collagen, and elastic fiber content in lung tissue, as well as decreased apoptotic cell counts in liver. Bone marrow and adipose tissue mesenchymal stem cells administration also reduced levels of tumor necrosis factor-α, interleukin-1β, keratinocyte-derived chemokine, transforming growth factor-β, and vascular endothelial growth factor, as well as apoptotic cell counts in lung and kidney, while increasing expression of keratinocyte growth factor in lung tissue. Additionally, mesenchymal stem cells differently modulated the secretion of biomarkers by macrophages depending on their source.

CONCLUSIONS

Mesenchymal stem cells from different sources led to variable responses in lungs and distal organs. Bone marrow and adipose tissue mesenchymal stem cells yielded greater beneficial effects than lung tissue mesenchymal stem cells. These findings may be regarded as promising in clinical trials.

Glutamine Administration Modulates Endothelial Progenitor Cell and Lung Injury in Septic Mice

This study investigated the effects of glutamine (GLN) administration on circulating endothelial progenitor cells (EPCs) and lung angiopoietin (Ang) gene expressions in polymicrobial sepsis. Mice were randomly assigned to a normal control group (NC), septic saline group (SS), and septic GLN group (SG). All mice were fed with a chow diet. Sepsis was induced by cecal ligation and puncture (CLP). The mice in SS group were injected with saline, whereas SG group administered 0.75 g GLN/kg body weight once via tail vein 1 h after CLP. Mice were killed 24 and 48 h after CLP. Their blood and lungs were collected for further analysis. The results showed that, compared with normal mice, sepsis resulted in higher C-X-C motif chemokine-12, vascular endothelial growth factor, nitric oxide levels, and a higher circulating EPC percentage. In addition, inflammatory cytokine concentrations and Ang-2 gene expression were upregulated in lung tissues. GLN administration enhanced the mobilization of EPC, and downregulated inflammatory cytokine production and the Ang-2 gene expressions in lungs. Histopathological findings showed that the extent of inflammatory lesions of the lung alveolar was less severe in the SG group than the SS group after CLP. Our results suggest that a single dose of intravenous GLN administration after initiation of sepsis promotes the mobilization of circulating EPC, and modulates the balance of Ang-Tie2 axis that may improve the vascular function, ameliorate inflammation, and protect lung injury against polymicrobial sepsis.

Effect of parenteral glutamine supplementation combined with enteral nutrition on Hsp90 expression and Peyer's patch apoptosis in severely burned rats

OBJECTIVES

The aim of this study was to investigate the effects of parenteral glutamine (GLN) supplementation combined with enteral nutrition (EN) on heat shock protein (Hsp) 90 expression and Peyer's patch (PP) apoptosis in severely burned rats.

METHODS

Male Sprague-Dawley (SD) rats were randomly assigned to four groups: Sham burn + EN + GLN-free amino acid (AA; n = 10), sham burn + EN + GLN (n = 10), burn + EN + AA (n = 10), and burn + EN + GLN (n = 10). Two hours after a 30% total body surface area (TBSA), full-thickness scald burn injury on the back, burned rats in two of the experimental groups (burn + EN + AA and burn + EN + GLN groups) were fed with a conventional EN solution by oral gavage for 7 d. Simultaneously, rats in the burn + EN + GLN group were given 0.35 g GLN/kg body weight/d once via a tail vein injection for 7 d and rats in the burn + EN + AA group were administered isocaloric/isonitrogenous GLN-free amino acid solution (Tyrosine) for comparison. Rats in two sham burn control groups (sham burn + EN + AA and sham burn + EN + GLN groups) were treated in the same manner except for the burn injury. All rats in the four groups were given 175 kcal/kg body wt/d. There was isonitrogenous, isovolumic, and isocaloric intake among the four groups. At the end of the seventh day after completion of the nutritional program, all rats were anesthetized and samples were collected for further analysis. PP apoptosis was measured by terminal deoxyuridine nick-end labeling (TUNEL). The expression of Hsp90 in PPs was analyzed by western blotting. Caspase-3 activity of PPs was also assessed. Levels of proinflammatory cytokines of gut tissues were evaluated by enzyme-linked immunosorbent assay (ELISA). The intestinal immunoglobulin A (IgA) content was also determined by ELISA.

RESULTS

The results revealed that intestinal IgA content in rats of the burn + EN + GLN group were significantly increased compared with those in the burn + EN + AA group (P < 0.05). The expression of Hsp90 of PPs in rats in the burn + EN + GLN group was significantly upregulated compared with those in the burn + EN + AA group (P < 0.05). On the other hand, levels of proinflammatory cytokines of gut tissues, caspase-3 activity, and the number of TUNEL-stained cells of PPs in rats of the burn + EN + GLN group were markedly decreased compared with those of the burn + EN + AA group (P < 0.05).

CONCLUSIONS

The results of this study show that parenteral glutamine supplementation combined with EN may upregulate the expression of Hsp90, reduce caspase-3 activity, lessen the release of proinflammatory cytokines, attenuate PP apoptosis, and improve intestinal IgA response in burned rats. Clinically, therapeutic efforts to improve intestinal immunity may contribute to a favorable outcome in severely burned patients.

Combined Enteral and Parenteral Glutamine Supplementation in Endotoxemic Swine: Effects on Portal and Systemic Circulation Levels

OBJECTIVE

To measure plasma glutamine (GLN) levels in systemic and portal circulation after combined enteral and parenteral administration in early endotoxemic swine. We hypothesized that this combination will be more efficient than intravenous administration alone in restoring plasma levels during the course of endotoxemia.

MATERIALS AND METHODS

Endotoxemia was induced with Escherichia coli O111:B4 lipopolysaccharide (LPS) (250 μg/kg body weight) in 16 anes-thetized, fasted swine and maintained by constant infusion (2 μg/kg/h) over 180 min. Another 16 swine served as controls. After infusion with LPS or placebo, GLN was administered intravenously, enterally or in combination (0.5 g/kg i.v. plus 0.5 g/kg enterally) over 30 min. At 0, 15, 30, 45, 60, 120 and 180 min, blood was drawn from the systemic and portal circulation for colorimetric assessment of GLN.

RESULTS

In healthy, placebo-alone swine, GLN levels remained stable throughout the study. Intravenous and combined infusion increased systemic levels (p = 0.001), but after enteral administration alone, a smaller effect was observed (p = 0.026). Portal levels were increased after combined, enteral and intravenous administration (p = 0.001). In endotoxemia, systemic and portal levels decreased significantly. Intravenous and, to a greater extent, combined administration increased systemic levels (p = 0.001), while enteral administration only had a small effect (p = 0.001). In the portal vein, intravenous and combined treatment increased plasma levels (p = 0.001), whereas enteral supplementation alone had again a small, yet significant effect (p = 0.001).

CONCLUSIONS

The findings indicate that combined GLN supplementation is superior to intravenous treatment alone, in terms of enhanced availability in systemic and portal circulations. Thus, combined treatment at the onset of endotoxemia is a beneficial practice, ensuring adequate GLN to compensate for the resulting intracellular shortage.

Effects of Malnutrition on Neutrophil/Mononuclear Cell Apoptotic Functions in Children with Acute Lymphoblastic Leukemia

BACKGROUND

Recent studies claim that apoptosis may explain immune dysfunction observed in malnutrition.

OBJECTIVE

The objective of this study was to determine the effect of malnutrition on apoptotic functions of phagocytic cells in acute lymphoblastic leukemia (ALL).

MATERIALS AND METHODS

Twenty-eight ALL patients (13 with malnutrition) and thirty controls were enrolled. Neutrophil and mononuclear cell apoptosis of ALL patients and the control group were studied on admission before chemotherapy and repeated at a minimum of three months after induction of chemotherapy or when the nutritional status of leukemic children improved.

RESULTS

The apoptotic functions of both ALL groups on admission were significantly lower than those of the control group. The apoptotic functions were lower in ALL patients with malnutrition than those in ALL patients without malnutrition, but this was not statistically significant. The repeated apoptotic functions of both ALL groups were increased to similar values with the control group. This increase was found to be statistically significant.

CONCLUSIONS

The apoptotic functions in ALL patients were not found to be affected by malnutrition. However, after dietary intervention, increased apoptotic functions in both ALL patient groups deserve mentioning. Dietary intervention should always be recommended as malnutrition or cachexia leads to multiple complications. Enhanced apoptosis might originate also from remission state of cancer.

Effect of parenteral glutamine supplementation combined with enteral nutrition on Hsp90 expression and lymphoid organ apoptosis in severely burned rats

OBJECTIVE

The aim of this study is to investigate the effects of parenteral glutamine(GLN) supplementation combined with enteral nutrition (EN) on heat shock protein 90(Hsp90) expression, apoptosis of lymphoid organs and circulating lymphocytes, immunological function and survival in severely burned rats.

METHODS

Male SD rats were randomly assigned into 4 groups: a sham burn+EN+GLN-free amino acid (AA) group (n=10), a sham burn+EN+GLN group (n=10), a burn+EN+AA group (n=10), and a burn +EN +GLN group (n=10). Two hours after a 30% total body surface area (TBSA), full-thickness scald burn injury on the back was made, the burned rats in two experimental groups (the burn+EN+AA group and the burn+EN +GLN group) were fed with a conventional enteral nutrition solution by oral gavage for 7 days. Simultaneously, the rats in the burn+EN+GLN group were given 0.35g GLN/kg body weight/day once via a tail vein injection for 7 days, whereas those in the burn+EN+AA group were administered isocaloric/isonitrogenous GLN-free amino acid solution (Tyrosine) for comparison. The rats in two sham burn control groups (the sham burn+EN+AA group and the sham burn+EN +GLN group) were treated in the same procedure as above, except for burn injury. All rats in each of the four groups were given 175kcal/kg body wt/day. There was isonitrogenous, isovolumic and isocaloric intake among four groups. At the end of the 7th day after nutritional programme were finished, all rats were anesthetized and samples were collected for further analysis. Serum immunoglobulin quantification was conducted by ELISA. Circulating lymphocyte numbers were counted by Coulter LH-750 Analyzer. The percentages and apoptotic ratio of CD4 and CD8T lymphocytes in circulation were determined by flow cytometry (FCM). The neutrophil phagocytosis index (NPI) was examined. The GLN concentrations in plasma, thymus, spleen and skeletal muscle were measured by high performance liquid chromatography (HPLC). The organ index evaluation and TUNEL analysis of thymus and spleen were carried out. The expression of Hsp90 in thymus and spleen was analyzed by western blotting. Moreover, the survival in burned rats was observed.

RESULTS

The results revealed that parenteral GLN supplementation combined with EN significantly increased the GLN concentrations of plasma and tissues, the serum immunoglobulin content, the circulating lymphocyte number, the CD4/CD8 ratio, the indexes of thymus and spleen, NPI and survival as compared with the burn+EN+AA group (p<0.05). The expression of Hsp90 in thymus and spleen in the burn+EN+GLN group was significantly up-regulated as compared with the burn+EN+AA group (p<0.05). The apoptosis in circulating CD4 and CD8 lymphocytes, thymus and spleen in the burn+EN+GLN group was significantly decreased as compared with the burn+EN+AA group (p<0.05).

CONCLUSION

The results of this study show that parenteral GLN supplementation combined with EN may increase the GLN concentrations of plasma and tissues, up-regulate the expression of Hsp90, attenuate apoptosis in lymphoid organ and circulating lymphocyte, enhance the immunological function and improve survival in severely burned rats. Clinically, therapeutic efforts at the modulation of the immune dysfunction may contribute to a favorable outcome in severely burned patients.

Reduced Hsp70 and Glutamine in Pediatric Severe Malaria Anemia: Role of Hemozoin in Suppressing Hsp70 and NF-κB activation

Severe malarial anemia [SMA, hemoglobin (Hb) <5.0 g/dL] is a leading cause of global morbidity and mortality among children residing in Plasmodium falciparum transmission regions. Exploration of molecular pathways through global gene expression profiling revealed that SMA was characterized by decreased HSPA1A, a heat shock protein (Hsp) 70 coding gene. Hsp70 is a ubiquitous chaperone that regulates Nuclear Factor-kappa B (NF-κB) signaling and production of pro-inflammatory cytokines known to be important in malaria pathogenesis (e.g., IL-1β, IL-6 and TNF-α). Since the role of host Hsp70 in malaria pathogenesis is unexplored, we investigated Hsp70 and molecular pathways in children with SMA. Validation experiments revealed that leukocytic HSP70 transcripts were reduced in SMA relative to non-severe malaria, and that intraleukocytic hemozoin (PfHz) was associated with lower HSP70. HSP70 was correlated with reticulocyte production and Hb. Since glutamine (Gln) up-regulates Hsp70, modulates NF-κB activation, and attenuates over-expression of pro-inflammatory cytokines, circulating Gln was measured in children with malaria. Reduced Gln was associated with increased risk of developing SMA. Treatment of cultured peripheral blood mononuclear cells (PBMCs) with PfHz caused a time-dependent decrease in Hsp70 transcripts/protein, and NF-κB activation. Gln treatment of PBMCs overcame PfHz-induced suppression of HSP70 transcripts/protein, reduced NF-κB activation, and suppressed over-expression of IL-1β, IL-6 and TNF-α. Findings here demonstrate that SMA is characterized by reduced intraleukocytic HSP70 and circulating Gln, and that PfHz-induced suppression of HSP70 can be reversed by Gln. Thus, Gln supplementation may offer important immunotherapeutic options for futures studies in children with SMA.

Whole-body and splanchnic amino acid metabolism in sheep during an acute endotoxin challenge

Supplemented protein or specific amino acids (AA) are proposed to help animals combat infection and inflammation. The current study investigates whole-body and splanchnic tissue metabolism in response to a lipopolysaccharide (LPS) challenge with or without a supplement of six AA (cysteine, glutamine, methionine, proline, serine and threonine). Eight sheep were surgically prepared with vascular catheters across the gut and liver. On two occasions, four sheep were infused through the jugular vein for 20 h with either saline or LPS from Escherichia coli (2 ng/kg body weight per min) in a random order, plus saline infused into the mesenteric vein; the other four sheep were treated with saline or LPS plus saline or six AA infused via the jugular vein into the mesenteric vein. Whole-body AA irreversible loss rate (ILR) and tissue protein metabolism were monitored by infusion of [ring-2H2]phenylalanine. LPS increased (P<0·001) ILR (+17 %), total plasma protein synthesis (+14 %) and lymphocyte protein synthesis (+386 %) but decreased albumin synthesis (-53 %, P=0·001), with no effect of AA infusion. Absorption of dietary AA was not reduced by LPS, except for glutamine. LPS increased the hepatic removal of leucine, lysine, glutamine and proline. Absolute hepatic extraction of supplemented AA increased, but, except for glutamine, this was less than the amount infused. This increased net appearance across the splanchnic bed restored arterial concentrations of five AA to, or above, values for the saline-infused period. Infusion of key AA does not appear to alter the acute period of endotoxaemic response, but it may have benefits for the chronic or recovery phases.

Exogenous Glutamine in Respiratory Diseases: Myth or Reality?

Several respiratory diseases feature increased inflammatory response and catabolic activity, which are associated with glutamine depletion; thus, the benefits of exogenous glutamine administration have been evaluated in clinical trials and models of different respiratory diseases. Recent reviews and meta-analyses have focused on the effects and mechanisms of action of glutamine in a general population of critical care patients or in different models of injury. However, little information is available about the role of glutamine in respiratory diseases. The aim of the present review is to discuss the evidence of glutamine depletion in cystic fibrosis (CF), asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), and lung cancer, as well as the results of exogenous glutamine administration in experimental and clinical studies. Exogenous glutamine administration might be beneficial in ARDS, asthma, and during lung cancer treatment, thus representing a potential therapeutic tool in these conditions. Further experimental and large randomized clinical trials focusing on the development and progression of respiratory diseases are necessary to elucidate the effects and possible therapeutic role of glutamine in this setting.

Glutamine may repress the weak LPS and enhance the strong heat shock induction of monocyte and lymphocyte HSP72 proteins but may not modulate the HSP72 mRNA in patients with sepsis or trauma

Objective. We assessed the lipopolysaccharide (LPS) or heat shock (HS) induction of heat shock protein-72 (HSP72) in peripheral blood mononuclear cells (PBMCs) of patients with severe sepsis (SS) or trauma-related systemic inflammatory response syndrome (SIRS), compared to healthy individuals (H); we also investigated any pre- or posttreatment modulating glutamine (Gln) effect. Methods. SS (11), SIRS (10), and H (19) PBMCs were incubated with 1 μg/mL LPS or 43°HS. Gln 10 mM was either added 1 h before or 1 h after induction or was not added at all. We measured monocyte (m), lymphocyte (l), mRNA HSP72, HSP72 polymorphisms, interleukins (ILs), monocyte chemoattractant protein-1 (MCP-1), and cortisol levels. Results. Baseline lHSP72 was higher in SS (p < 0.03), and mHSP72 in SIRS (p < 0.02), compared to H. Only HS induced l/mHSP72/mRNA HSP72; LPS induced IL-6, IL-8, IL-10, and MCP-1. Induced mRNA was related to l/mHSP72, and was related negatively to cytokines. Intracellular l/mHSP72/HSP72 mRNA was related to serum ILs, not being influenced by cortisol, illness severity, and HSP72 polymorphisms. Gln did not induce mRNA in any group but modified l/mHSP72 after LPS/HS induction unpredictably. Conclusions. HSP72 mRNA and l/mHSP72 are higher among critically ill patients, further induced by HS, not by LPS. HSP72 proteins and HSP72 mRNA are related to serum ILs and are negatively related to supernatant cytokines, not being influenced by HSP72 polymorphisms, cortisol, or illness severity. Gln may depress l/mHSP72 after LPS exposure and enhance them after HS induction, but it may not affect early induced HSP72 mRNA.

Effects of enteral nutrition with parenteral glutamine supplementation on the immunological function in septic rats

The aim of the present study was to investigate the effects of enteral nutrition (EN) with parenteral glutamine (GLN) supplementation on inflammatory response, lymphatic organ apoptosis, immunological function and survival in septic rats by caecal ligation and puncture (CLP). Male rats were randomly assigned into two experimental groups and two sham CLP control groups (n 10 per group). After CLP or sham CLP model and nutrition programme were completed, the GLN concentrations of plasma and tissues and several indices of immunological function including serum Ig content, circulating lymphocyte number, the CD4:CD8 ratio, the neutrophil phagocytosis index (NPI), the organ index and apoptosis of thymus and spleen, and plasma cytokine levels were determined. Moreover, the survival in septic rats was observed. The results revealed that EN with parenteral GLN supplementation remarkably increased the GLN concentrations of plasma and tissues, serum Ig content, the circulating lymphocyte number, the CD4:CD8 ratio, the indexes of thymus and spleen, NPI and survival compared with the control group (P< 0·05). In contrast, the apoptosis of thymus and spleen and the levels of TNF-α, IL-1β and IL-6 in plasma were obviously decreased compared with the control group (P< 0·05). These results show that EN with parenteral GLN supplementation diminished the release of inflammatory cytokines, attenuated lymphatic organ apoptosis, enhanced the immunological function and improved survival in septic rats.

Brief Glutamine Pretreatment Increases Alveolar Macrophage CD163/Heme Oxygenase-1/p38-MAPK Dephosphorylation Pathway and Decreases Capillary Damage but Not Neutrophil Recruitment in IL-1/LPS-Insufflated Rats

Background

Glutamine (GLN) attenuates acute lung injury (ALI) but its effect on alveolar macrophages is unknown. We hypothesized that GLN pretreatment would induce the anti-inflammatory CD163/heme oxygenase (HO)-1/p38-MAPK dephosphorylation pathway in alveolar macrophages and reduce ALI in rats insufflated with interleukin-1 (IL-1) and lipopolysaccharide (LPS).

Methods

Male Sprague-Dawley rats were randomized to the following groups: GLN-IL-1/LPS-, GLN+IL-1/LPS-, GLN-IL-1/LPS+, and GLN+IL-1/LPS+. GLN pretreatment was given via gavage (1g/kg L-alanyl-L-glutamine) daily for 2 days. ALI was subsequently induced by insufflating 50ng IL-1 followed by 5mg/kg E.coli LPS. After 24h, bronchoalveolar lavage (BAL) protein, lactate dehydrogenase (LDH) and neutrophil concentrations were analyzed. BAL alveolar macrophage CD163+ expression, HO-1 and p38-MAPK concentrations were measured, as well as alveolar macrophage tumor necrosis factor (TNF)-α and interleukin (IL)-10 concentrations. Histology and immunofluorescence studies were also performed.

Results

Following IL-1/LPS insufflation, GLN pretreated rats had significantly decreased BAL protein and LDH concentrations, but not BAL neutrophil counts, compared to non-GLN pretreated rats. The number of alveolar macrophages and the number of CD163+ macrophages were significantly increased in GLN pretreated IL-1/LPS-insufflated rats compared to non-GLN pretreated, IL-1/LPS-insufflated rats. GLN pretreatment before IL-1/LPS also significantly increased HO-1 concentrations and dephosphorylated p38-MAPK levels but not cytokine levels in alveolar macrophages. Immunofluorescence localized CD163 and HO-1 in alveolar macrophages.

Conclusion

Short-term GLN pretreatment activates the anti-inflammatory CD163/HO-1/p38-MAPK dephosphorylation pathway of alveolar macrophages and decreases capillary damage but not neutrophil recruitment in IL-1/LPS-insufflated rats.

Parenteral glutamine supplementation in combination with enteral nutrition improves intestinal immunity in septic rats

OBJECTIVES

The gut-associated lymphoid tissue is continuously exposed to antigens in the gut lumen and becomes the first line of defense against enteric bacteria and associated toxin. The aim of this study was to investigate the effects of parenteral glutamine (GLN) supplementation in combination with enteral nutrition (EN) on intestinal mucosal immunity in septic rats by cecal ligation and puncture (CLP).

METHODS

Male Sprague-Dawley rats were randomly assigned into four groups: A sham CLP + EN + saline group (n = 10), a sham CLP + EN + GLN group (n = 10), a CLP + EN + saline group (n = 10), and a CLP + EN + GLN group (n = 10). At 2 h after CLP or sham CLP, all rats in each of the four groups received an identical enteral nutrition solution as their base formula. Then, the rats in the sham CLP + EN + GLN group and CLP + EN + GLN group were given 0.35 g GLN/kg body weight daily for 7 d, all at the same time, via a tail vein injection; whereas those in the sham CLP + EN + saline group and CLP + EN + saline group were daily administered isovolumic sterile 0.9% saline for comparison. All rats in each of the four groups were given 290 kcal/kg body wt/d for 7 d. At the end of the seventh day after the nutritional program was finished, all rats were euthanized and the entire intestine was collected. Total Peyer's patches (PP) cell yield was counted by a hemocytometer. The percentage of PP lymphocyte subsets was analyzed by flow cytometry. The number of intestinal lamina propria IgA plasma cells was determined by the immunohistochemistry technique. The intestinal immunoglobulin A (IgA) levels were assessed by ELISA. PP apoptosis was evaluated by terminal deoxyuridine nick-end labeling.

RESULTS

The results revealed total PP cell yield, the numbers of PP lymphocyte subsets, intestinal lamina propria IgA plasma cells, and intestinal IgA levels in the CLP + EN + GLN group were significantly increased when compared with the CLP + EN + saline group (P < 0.05). On the other hand, the number of TUNEL-stained cells within PPs in the CLP + EN + GLN group was markedly decreased as compared with the CLP + EN + saline group (P < 0.05).

CONCLUSION

The results of this study show that parenteral glutamine supplementation in combination with enteral nutrition may attenuate PP apoptosis, increase PP cell yield and intestinal lamina propria IgA plasma cells, and subsequently improve intestinal mucosal immunity. Clinically, these results suggest therapeutic efforts at improving intestinal immunity may contribute to the prevention and treatment of sepsis.

[What is your diagnosis? (Cutaneous leishmaniasis)]

Neutrophils are the most abundant, short lived, and terminally differentiated leukocytes with distinct tiers of arsenals to counter pathogens. Neutrophils were traditionally considered transcriptionally inactive cells, but recent researches in the field led to a paradigm shift in neutrophil biology and revealed subpopulation heterogeneity, and functions pivotal to immunity and inflammation. Furthermore, recent unfolding of metabolic plasticity in neutrophils has challenged the long-standing concept of their sole dependence on glycolytic pathway. Metabolic adaptations and distinct regulations have been identified which are critical for neutrophil differentiation and functions. The metabolic reprogramming of neutrophils by inflammatory mediators or during pathologies such as sepsis, diabetes, glucose-6-phosphate dehydrogenase deficiency, glycogen storage diseases (GSDs), systemic lupus erythematosus (SLE), rheumatoid arthritis, and cancer are now being explored. In this review, we discuss recent developments in understanding of the metabolic regulation, that may provide clues for better management and newer therapeutic opportunities for neutrophil centric immuno-deficiencies and inflammatory disorders.