Alanine-glutamine dipeptide (AGD) inhibits expression of inflammation-related genes in hemorrhagic shock

The relationship between plasma amino acids and circulating albumin and haemoglobin in postabsorptive stroke patients

Background

This retrospective study had two main aims: (1) to document possible correlations between plasma Amino Acids (AAs) and circulating Albumin (Alb) and Haemoglobin (Hb); and (2) to identify which AAs were predictors of Alb and Hb.

Methods

The study considered 125 stroke subjects (ST) (61.6% males; 65.6 +/- 14.9 years) who met the eligibility criteria (absence of co morbidities associated with altered plasma AAs and presence of plasma AAs determined after overnight fasting). Fifteen matched healthy subjects with measured plasma AAs served as controls.

Results

The best correlations of Alb were with tryptophan (Trp) and histidine (His) (r = + 0.53; p < 0.0001), and those of Hb were with histidine (r = +0.47) and Essential AAs (r = +0.47) (both p<0.0001). In multivariate analysis, Trp (p< 0.0001) and His (p = 0.01) were shown to be the best positive predictors of Alb, whereas glutamine (p = 0.006) was the best positive predictor of Hb.

Conclusions

The study shows that the majority of plasma AAs were positively correlated with Alb and Hb. The best predictors of circulating Alb and Hb were the levels of tryptophan and glutamine, respectively.

Residual gastric volume evaluation with ultrasonography after ingestion of carbohydrate- or carbohydrate plus glutamine-enriched beverages: a randomized, crossover clinical trial with healthy volunteers

BACKGROUND

- Abbreviation of preoperative fasting to 2 hours with maltodextrin (CHO)-enriched beverage is a safe procedure and may enhance postoperative recovery. Addition of glutamine (GLN) to CHO beverages may include potential benefits to the metabolism. However, by adding a nitrogenous source to CHO beverages, gastric emptying may be delayed and increase the risk of bronchoaspiration during anesthesia.

OBJECTIVE

- In this study of safety, we aimed at investigating the residual gastric volume (RGV) 2 hours after the intake of either CHO beverage alone or CHO beverage combined with GLN.

METHODS

- We performed a randomized, crossover clinical trial. We assessed RGV by means of abdominal ultrasonography (US) in 20 healthy volunteers (10 males and 10 females) after an overnight fast of 8 hours. Then, they were randomized to receive 600 mL (400 mL immediately after US followed by another 200 mL 2 hours afterwards) of either CHO (12.5% maltodextrin) or CHO-GLN (12.5% maltodextrin plus 15 g GLN). Two sequential US evaluations were done at 120 and 180 minutes after ingestion of the second dose. The interval of time between ingestion of the two types of beverages was 2 weeks.

RESULTS

- The mean (SD) RGV observed after 8 hours fasting (13.56±13.25 mL) did not statistically differ (P>0.05) from the RGV observed after ingesting CHO beverage at both 120 (16.32±11.78 mL) and 180 minutes (14.60±10.39 mL). The RGV obtained at 120 (15.63±18.83 mL) and 180 (13.65±10.27 mL) minutes after CHO-GLN beverage also was not significantly different from the fasting condition.

CONCLUSION

- The RGV at 120 and 180 minutes after ingestion of CHO beverage combined with GLN is similar to that observed after an overnight fast.

The study of n-3PUFAs protecting the intestinal barrier in rat HS/R model

BACKGROUND

N-3 PUFAs have been demonstrated in vitro it could prevent the intestinal tight junctions (TJs) from the ischemia/re-perfusion injury and the inflammatory reaction injury. The purpose of this study was to evaluate the protection of n-3 PUFAs on the intestinal TJs in the rat model of hemorrhagic shock followed by resuscitation.

METHODS

Male SD rats (n = 72; 250 ~ 300 g) were randomly divided into 6 groups: SHAM, hemorrhagic shock (HS), hemorrhagic shock/resuscitation (HS/R), ω-6 group, ω-3 group and ω-3 treatment group. Shock was induced, and a mean arterial pressure was maintained at 35 to 40 mmHg for 60 minutes. Resuscitation was carried out by returning half of the shed blood and Ringer's lactate solution. In ω-6 and ω-3 group, Intralipid or fish oil (0.2 g/Kg), respectively, was infused 30 minutes after shock. And fish oil was infused with resuscitation in ω-3 treatment group. Half of each group was killed at 30 minutes and 4 hours after resuscitation, respectively. The serum samples and the intestinal sample was collected for further examination.

RESULT

There is no difference between ω-3, ω-3 treatment and sham group in Chiu's score, but the other three groups have higher scores than they did. Compared with HS, HSR and ω-6 group, ω-3 and ω-3 treatment group showed most intact in intestinal mucoscal villi and TJs through HE, SEM and LSCM. The levels of IL-6 and TNF-α of bowel tissue in ω-3 and ω-3 treatment group were significantly lower than HS and HSR groups'. At the time point of 30 min, the levels of serum endotoxin were dramatically higher in HS、 HSR and ω-6 groups when compared with ω-3, ω-3 treatment and sham group. However, it in ω-3 group was greater than sham and HS group until 4 hours.

CONCLUSION

Fish oil pretreatment before resuscitation showed a beneficial effect to the intestinal TJs and atteunated inflammation after H/R in HS/R rat model and is better than ω-6 PUFAs did.

Alleviation of lung inflammatory responses by adeno-associated virus 2/9 vector carrying CC10 in OVA-sensitized mice

Asthma is a chronic airway inflammatory disease characterized by eosinophilic infiltration and airway hyperresponsiveness. The over-activated Th2 and lung epithelium cells express many different cytokines, and chemokines mainly contribute to the severity of lung inflammation. Clara cell 10 kD protein (CC10) is highly expressed in airway epithelium cells and exhibits anti-inflammatory and immunomodulatory effects. Adeno-associated virus (AAV) 2/9 vector, composed of AAV2 rep and AAV9 cap genes, can efficiently and specifically target lung epithelium cells. Thus, AAV2/9 vector might carry therapeutic potential gene sequences for the treatment of asthma. This study tested whether AAV2/9 vector carrying CC10 could reduce inflammatory and asthmatic responses in OVA-induced asthmatic mouse model. The results showed that AAV2/9-CC10 vector virus significantly reduced airway hyperresponsiveness, CCL11, interleukin (IL)-4, IL-5, IL-6, IL-13, and eosinophilia in the lungs of sensitized mice. CC10 level in OVA-sensitized mice was rescued with the administration of AAV2/9-CC10 vector virus. Lung tissue remodeling, including collagen deposition and goblet cell hyperplasia, was also alleviated. However, serum levels of OVA-specific IgG1 and IgE as well as Th2 cytokine levels in OVA-stimulated splenocyte culture supernatants were at the comparable levels to the sensitized control group. The results demonstrate that AAV2/9-CC10 vector virus relieved local inflammatory and asthmatic responses in lung. Therefore, we propose that AAV2/9-CC10 vector virus guaranteed sufficient CC10 expression and had an anti-inflammatory effect in asthmatic mice. It might be applied as a novel therapeutic approach for asthma.

Fish oil improves hemodynamic stabilization and inflammation after resuscitation in a rat model of hemorrhagic shock

Background

Hemorrhagic shock followed by resuscitation stimulates an inflammatory response. This study tests the hypothesis that treatment with fish oil will attenuate inflammatory responses and stabilize hemodynamics.

Methods

Male SD rats (n = 48; 250~300 g) were randomly divided into 4 groups: SHAM, hemorrhagic shock (HS), hemorrhagic shock/resuscitation (HS/R) and fish oil (FO). Shock was induced, and a mean arterial pressure (MAP) was maintained at 35 to 40 mmHg for 60 minutes. Resuscitation was carried out by returning half of the shed blood and Ringer's lactate solution to the animal. In FO group, fish oil (0.2 g/Kg) was infused through caudal vena at 30 minutes after shock. Half of each group was killed at 30 minutes and at 4 hours after resuscitation. Then several kinds of inflammation and oxidative stress indicators such as IL-6, MPO and GSH were tested.

Result

FO group required less resuscitative fluid and had higher urinary output at the recovery periods from hemorrhagic shock than HS/R group(p < 0.001). After resuscitation, the MAP of HS/R group markedly declined than FO group (p < 0.001). The inflammatory indexes of FO group were lower than HS group and HS/R group and the same as sham group. But the level of endotoxin in FO group was significantly higher than sham group at 4 hours.

Conclusion

Fish oil pretreatment before fluid resuscitation showed a beneficial effect to the hemodynamic stabilization and inflammation reduction in HS/R rat model.

Amino acid-anticodon binding specificity: rationale for a new class of therapeutic agent

In this article a new class of anticancer and antiviral drugs is discussed. These new drugs consist of small di- and tri-peptides, designed to bind to single-stranded (ss) regions that are crucial for the expression of genes such as the c-myc oncogene in cancers and start sites (and other ss regions) of viral pathogenic genes. The components (i.e. the amino acids and the sequences they form) of these peptides could be dictated by the specific binding of amino acids to their ss anticodons in tRNA. Cancer cell viability depends on the continued overexpression of the c-myc oncogene, and thus this gene is a target of opportunity for anticancer agents. Sharply reducing the overexpression of c-myc leads to the death of cancer cells. To achieve this end the following rationale is suggested: crucial regions of the c-myc promoters (to which activating proteins must bind for expression to occur) are single stranded and thus strongly resemble the anticodon loop of tRNA. It was found that amino acids chemically bind to their cognate tRNA anticodons. Regarding the ss regions of c-myc as a series of adjacent 'anticodons', di- and tri-peptides are proposed to be aligned to their cognate 'anticodons' in the proper order. For example, if the ss region of a promoter is hypothetically TTT-GGG-CCC, the tripeptide Lys-Pro-Gly could be expected to bind to it and deny access of the promoter to all activating proteins, thereby blocking c-myc expression and all the cancers dependent on such overexpression. Similarly, it is reported that in the initial phase of gene expression the start sites of the genes are single stranded (before and after and spanning the start site). Thus, invoking the amino acid cognate anticodon binding specificity (ACABS) principle as described above, a series of small peptides are suggested that could span the start sites of pathogenic viral genes (e.g. the oris region of herpes simplex virus (HSV)) to deny access of the gene to the transcription elements. This would inactivate the toxic effect of the virus and thereby constitute a promising approach to antiviral therapy, where the start sites (or other ss regions of pathogenic genes) have been sequenced. The ACABS principle (for peptide-nucleic-acid interaction) enables us to focus on probable effective small peptides rather than having to screen a large number of randomly chosen small peptides to find probable anticancer and antiviral therapeutic agents.

Prefeeding with omega-3 fatty acids suppresses inflammation following hemorrhagic shock

BACKGROUND

Hemorrhagic shock followed by resuscitation stimulates an inflammatory response. This study tests the hypothesis that prefeeding with fish oil rich in ω-3 fatty acids (FAs) will attenuate that response.

METHODS

Male Sprague-Dawley rats (n = 60; 350 ± 30 g) were randomly but unequally assigned to 3 groups: sham (n = 12), control (n = 24), and fish oil (n = 24). In the fish oil group, rat chow was supplemented with fish oil (600 mg/kg/d, 25% ω-3 FA). Control and sham group diets were supplemented with corn oil. Under fluothane, hemorrhagic shock was induced, and arterial pressure was maintained at 25 to 30 mm Hg for 30 minutes. Resuscitation was carried out by giving 21 mL/kg lactated Ringer's solution and returning shed blood to the animal. Half of each group was killed at 30 minutes and at 4 hours postresuscitation. Liver samples were assayed for indicators of inflammation and heat shock protein 25 (Hsp25). Lung edema was measured.

RESULTS

All animals survived. At 30 minutes postresuscitation, expression of mRNA for inducible nitric oxide synthase (iNOS) was significantly elevated in the control group but normal in the fish oil group. At 4 hours, expression of mRNA for Hsp25 was significantly increased in the fish oil group. Lung edema index was significantly lower in the fish oil group than in either sham or control groups.

CONCLUSIONS

Fish oil prefeeding in a rodent model of hemorrhagic shock was associated with increased liver mRNA expression of Hsp25, reduced liver mRNA expression of iNOS, and decreased lung edema. These findings support the validity of the study hypothesis.

Prevention of hemorrhagic shock-induced intestinal tissue injury by glutamine via heme oxygenase-1 induction

Hemorrhagic shock (HS) is an oxidative stress that causes intestinal tissue injury. Heme oxygenase 1 (HO-1) is induced by oxidative stress and is thought to play an important role in the protection of tissues from oxidative injury. We previously reported the ileum to be the most susceptible to HS-induced tissue injury site in the intestine because HO-1 induction is the lowest at this site. We also previously demonstrated that glutamine (GLN) significantly induced HO-1 in the lower intestinal tract. In the present study, we investigated whether GLN pretreatment improves HS-induced intestinal tissue injury in the ileum by HO-1 induction. Treatment of rats with GLN (0.75 g/kg, i.v.) markedly induced functional HO-1 protein in mucosal epithelial cells in the ileum. Glutamine treatment before HS (MAP of 30 mmHg for 60 min) significantly ameliorated HS-induced mucosal inflammation and apoptotic cell death in the ileum, as judged by significant decreases in gene expression of TNF-alpha, iNOS, intercellular adhesion molecule 1, and vascular cell adhesion molecule 1, myeloperoxidase activity, the number of infiltrated neutrophils, DNA fragmentation by in situ oligo ligation assay, and activated caspase-3 expression, and by increases in gene expression of IL-10 and Bcl-2. In contrast, treatment with tin mesoporphyrin, a specific inhibitor of HO activity, abolished the beneficial effect of GLN pretreatment. These findings indicate that GLN pretreatment significantly ameliorated tissue injury in the ileum after HS by inducing HO-1. Glutamine treatment may thus protect mucosal cells from HS-induced oxidative damage via the anti-inflammatory and antiapoptotic properties of HO-1.

Glutamine: role in critical illness and ongoing clinical trials

PURPOSE OF REVIEW

This review will assess recent clinical and mechanistic data examining glutamine's ability to reduce morbidity and mortality in critical illness.

RECENT FINDINGS

Updated metaanalysis data reveal a significant benefit of glutamine supplementation on mortality, length of stay, and infectious morbidity in critical illness. Recent data support glutamine's use in critically ill patients requiring parenteral nutrition and new data reveal safety and efficacy in head-injured patients. Further, new findings on glutamine's beneficial effect on insulin resistance in critical illness will be reviewed. Recent laboratory data have clarified a number of key mechanistic pathways by which glutamine may improve outcome in critical illness.

SUMMARY

Severe glutamine deficiencies occur rapidly in critical illness. The magnitude of glutamine deficiency is correlated with ICU mortality. Further, metaanalysis reveals glutamine reduces morbidity and mortality in critical illness. It is likely that our new understanding of the molecular pathways by which glutamine acts will lead to insight on how best to utilize glutamine as a nutritional therapy. Presently, randomized, multicenter clinical trials utilizing glutamine as both nutritional replacement and pharmacologic intervention, independent of nutritional needs, are ongoing.

Glutamine: mode of action in critical illness

A recent editorial in Critical Care Medicine was titled "Glutamine, a life-saving nutrient, but why?" (2003; 31:2555-2556). This review will attempt to utilize new understanding of gene-nutrient interactions and molecular medicine to address potential mechanisms by which glutamine may be lifesaving after critical illness and injury. Recent meta-analysis data reveal that glutamine seems to exert a beneficial effect on mortality in critically ill patients. However, this effect seems to be dose and route dependent. The questions that remain to be answered are in what settings and via what method of administration does this phamaconutrient show optimal benefit? It is likely that examination of the molecular mechanisms by which glutamine exerts its effects will lead to an understanding of how best to utilize glutamine as both a pharmacologic and a nutritional agent. Clearly, clinical critical illness leads to a marked deficiency in glutamine that is correlated with mortality in the intensive care unit setting. It makes obvious sense that the deficiency of this vital stress nutrient should be replaced. In addition, recent laboratory data reveal glutamine may act via mechanisms independent of its role as a metabolic fuel. These include enhanced stress protein response, attenuation of the inflammatory response, improved tissue metabolic function, and attenuation of oxidant stress. Present data indicate that glutamine functions as a metabolic fuel and "stress-signaling molecule" after illness and injury. Thus, deficiencies observed in critical illness demand replacement for both pharmacologic and metabolic optimization. Presently, randomized, multicenter, clinical trials utilizing glutamine as a pharmacologic and a nutritional agent are ongoing.

Administration of glutamine after hemorrhagic shock restores cellular energy, reduces cell apoptosis and damage, and increases survival

BACKGROUND

Hemorrhagic shock causes a rapid depletion of adenosine triphosphate (ATP) and an increase of the terminal metabolite xanthine. Free radicals generated from xanthine oxidase play a major role in cell injury. Programmed cell death, apoptosis, is a major pathway causing reperfusion injury. During apoptosis, cytosolic cytochrome-c is released from damaged mitochondria, and it further initiates activation of apoptosis as evidenced by the appearance of caspase-3. The bcl-2 protein serves as an antiapoptosis found on the mitochondrial membrane. Glutamine has been known as a conditionally essential nutrient and seems to have beneficial effects in critically ill patients. The hypothesis of the present study is that glutamine administered during resuscitation following hemorrhagic shock would restore the depletion of hepatic ATP, reduce cellular apoptosis, and increase survival.

METHODS

Male Sprague-Dawley rats were randomly assigned to 3 groups for resuscitation after the same pattern of hemorrhagic shock: Ringer's lactate (LR 21 ml/kg); Alanine-glycine (LR with alanine 0.15 gm/kg and glycine 0.18 gm/kg); and glutamine (LR with glutamine 0.3 gm/kg). Hepatic ATP and xanthine was measured at different time periods. Hepatic apoptosis was measured and the levels of cytosolic cytochrome-c, caspase-3 and bcl-2 were analyzed. Another group of rats were used for survival study.

RESULTS

Glutamine administered during resuscitation following hemorrhagic shock partially restored the depletion of hepatic ATP, reduced cellular apoptosis, and increased survival.

CONCLUSIONS

Glutamine administration during resuscitation significantly protected the liver from tissue damage caused by hemorrhagic shock. Glutamine supplementation may offer opportunities for therapeutic intervention during and after shock.