Combined glutamine and arginine decrease proinflammatory cytokine production by biopsies from Crohn's patients in association with changes in nuclear factor-kappaB and p38 mitogen-activated protein kinase pathways

[Impact of short-peptide exclusive enteral nutrition therapy on physical growth and nutritional status in children with Crohn's disease]

OBJECTIVES

To evaluate the clinical efficacy of short-peptide exclusive enteral nutrition (EEN) therapy in inducing remission during active Crohn's disease (CD) in children, as well as changes in physical growth and nutritional indicators before and after treatment.

METHODS

A prospective study included 43 children with active CD who were admitted to the Department of Gastroenterology, Children's Hospital of Nanjing Medical University from January 2017 to January 2024. The participants were randomly divided into a medication treatment group (13 children) and a short-peptide + medication treatment group (30 children). The changes in the Pediatric Crohn's Disease Activity Index (PCDAI) scores, physical growth, and nutritional indicators before and after treatment were analyzed in both groups.

RESULTS

The PCDAI scores in the short-peptide + medication treatment group were lower than those in the medication treatment group after treatment (P<0.05). The Z-scores for weight-for-age, body mass index, and albumin levels were higher in the short-peptide + medication treatment group compared to the medication treatment group (P<0.05). In the patients with moderate to severe CD, total protein levels in the short-peptide + medication treatment group were significantly higher than those in the medication treatment group (P<0.05).

CONCLUSIONS

Short-peptide EEN therapy can induce clinical remission in children with active CD and promote their physical growth while improving their nutritional status.

Glutamine-derived peptides: Current progress and future directions

Glutamine, the most abundant amino acid in the body, plays a critical role in preserving immune function, nitrogen balance, intestinal integrity, and resistance to infection. However, its limited solubility and instability present challenges for its use a functional nutrient. Consequently, there is a preference for utilizing glutamine-derived peptides as an alternative to achieve enhanced functionality. This article aims to review the applications of glutamine monomers in clinical, sports, and enteral nutrition. It compares the functional effectiveness of monomers and glutamine-derived peptides and provides a comprehensive assessment of glutamine-derived peptides in terms of their classification, preparation, mechanism of absorption, and biological activity. Furthermore, this study explores the potential integration of artificial intelligence (AI)-based peptidomics and synthetic biology in the de novo design and large-scale production of these peptides. The findings reveal that glutamine-derived peptides possess significant structure-related bioactivities, with the smaller molecular weight fraction serving as the primary active ingredient. These peptides possess the ability to promote intestinal homeostasis, exert hypotensive and hypoglycemic effects, and display antioxidant properties. However, our understanding of the structure-function relationships of glutamine-derived peptides remains largely exploratory at current stage. The combination of AI based peptidomics and synthetic biology presents an opportunity to explore the untapped resources of glutamine-derived peptides as functional food ingredients. Additionally, the utilization and bioavailability of these peptides can be enhanced through the use of delivery systems in vivo. This review serves as a valuable reference for future investigations of and developments in the discovery, functional validation, and biomanufacturing of glutamine-derived peptides in food science.

High methionine diet mediated oxidative stress and proteasome impairment causes toxicity in liver

Methionine (Met) rich diet inducing oxidative stress is reported to alter many organs. Proteasome as a regulator of oxidative stress can be targeted. This study was performed to investigate if excessive methionine supplementation causes hepatotoxicity related to proteasome dysfunction under endogenous oxidative stress in rats. Male Wistar albino rats (n = 16) were divided into controls and treated groups. The treated rats (n = 08) received orally L-methionine (1 g/kg/day) for 21 days. Total homocysteine (tHcy), total oxidant status (TOS), total antioxidant status (TAS), hepatic enzymes levels: aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), alkaline phosphatase (ALP), with total bilirubin (TBil), albumin (Alb), and C-reactive protein (CRP) were determined in plasma by biochemical assays. Liver supernatants were used for malondialdehyde (MDA), protein carbonyls (PC), glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), 20S proteasome activities and their subunits expression, tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6) evaluation by appropriate methods and light microscopy for liver histological examination. Methionine treatment increased homocysteine, TOS, oxidative stress index (OSI), MDA and PC but decreased TAS, GSH, CAT, SOD, GPx with the 20S proteasome activities and their β subunits expression. Liver proteins: AST, ALT, LDH, ALP, TBil and CRP were increased but Alb was decreased. Liver histology was also altered. An increase in liver TNF-α and IL-6 levels were observed. These findings indicated that methionine supplementation associated oxidative stress and proteasome dysfunction, caused hepatotoxicity and inflammation in rat. Further investigations should be to better understand the relation between methionine, oxidative stress, proteasome, and liver injuries.

Amino acid profiles, disease activity, and protein intake in adult patients with Crohn's disease

Introduction

Crohn's disease (CD) is an immune-mediated inflammatory disorder of the gastrointestinal tract with a relapsing-remitting course. Amino acids (AAs) may play critical roles in the intestinal manifestations of disease, due to their involvement in many metabolic and immune functions. The present study aimed to explore serum AA concentrations in adult patients with CD, looking into their variations due to disease activity, surgery and protein content of diet. Eventually, the link between AAs and inflammatory markers was also assessed.

Methods

Consecutive adult patients aged 18-65 years with diagnosis of CD were recruited. All participants underwent anthropometry and were instructed to fill in a 3-day food record to assess protein intake. Disease activity was clinically defined using the Crohn's Disease Activity Index (CDAI), while blood samples were taken to analyze serum AA profile and inflammatory markers.

Results

A total of 103 patients with CD (61 men and 42 women; age:39.9 ± 13.9 years, BMI: 23.4 ± 3.51 kg/m2) were included. Tryptophan levels were found to be remarkably decreased in most subjects, unrelated to disease activity. On the contrary, concentration of lysine, leucine, valine and glutamine decreased in active versus quiescent CD patients, while aspartic acid, glutamate and glycine increased. The latter AAs were also directly correlated with CDAI and serum interleukin (IL)- 1β concentration. Considering the total protein intake, expressed as g/kg/body weight, we observed a reduction in some essential AAs in patients with unmet protein requirements compared to patients who met the recommendation.

Discussion

In conclusion, specific AAs varied according to disease activity and protein intake, adjusted to body weight and disease status. Glu and Asp concentrations raised with increasing IL-1β. However, extensive research is needed to understand the mechanisms underpinning the link between variation in serum AAs, disease activity and protein intake in patients with CD.

Impact of Preoperative Immunonutrition on Oxidative Stress and Gut Barrier Function in Surgical Patients with Crohn's Disease

Several international guidelines recommend a peri-operative immunonutrition (IN) support for patients care in elective colorectal surgery, to reduce postoperative complications, particularly infections. In Crohn's patients, is also used to mitigate the severity of the disease. We performed a pilot study on 16 Crohn's patients undergoing intestinal surgery for active disease, not responsive to pharmacological treatment; half of them received an oral nutritional supplement enriched with immunonutrients (IN patients) for 7 days prior to surgery, in addition to normal food intake. Markers of oxidative stress (Advanced Glycated End-products (AGEs) and Advanced Oxidation Protein Products (AOPPs) were measured both in plasma and tissue samples wherein the Receptor for Advanced Glycation End products (RAGE) and Tight Junction Protein 1 (TJP1) gene expression were also determined. Plasma AGEs were significantly and positively correlated with tissue levels of AGEs (p = 0.0354) and AOPPs (p = 0.0043) while they were negatively correlated with TJP1 expression (p = 0.0159). The expression of RAGE was also negatively correlated with that of TJP1 gene (p = 0.0146). IN patients exhibited significantly lower AGEs plasma levels (p = 0.0321) and a higher mucosal TJP1 expression (p = 0.0182). No patient had postoperative complications and the length of hospital stay was similar in the two groups, but IN patients, showed a significantly shorter time to resume fluid and solid diet. These preliminary data suggest that IN might support patient's recovery by improving intestinal mucosa barrier function through the regulation of AGEs/RAGE signaling.

Evaluation of the recovery after heart surgery following preoperative supplementation with a combination of beta-hydroxy-beta-methylbutyrate, L-arginine, and L-glutamine: a double-blind randomized placebo-controlled clinical trial

BACKGROUND

The preoperative period is a good time to improve nutrition status, compensate for nutrient deficiencies, and optimize immune function in patients' underlying surgery. In some medical conditions, supplementation with a combination of L-glutamine (Gln), β-hydroxy-β-methylbutyrate (HMB), and L-arginine (Arg) had promising effects on improving recovery. The present study aimed to evaluate the effect of supplementation with Gln/Arg/HMB in patients undergoing heart surgery.

METHODS

This randomized clinical trial was conducted on 70 patients undergoing cardiac surgery. Participants were requested to consume 2 sachets of a combination of 7 g L-arginine, 7 g L-glutamine, and 1.5 g daily HMB or placebo 30 days before operation. At the baseline and end of the study, left ventricular ejection fraction and the serum levels of troponin, creatine phosphokinase (CPK), CPK-MB, alanine aminotransferase (ALT), aspartate aminotransferase (AST), and bilirubin were measured. Also, the Sequential Organ Failure Assessment (SOFA) score, time of stay in hospital and intensive care unit (ICU), and postoperative complications were recorded after surgery.

RESULTS

In total, 60 preoperative patients (30 in each group) with a mean age of 53.13 ± 14.35 years completed the study (attrition rate = 85.7%). Subjects in the Gln/Arg/HMB group had lower serum levels of CPK-MB (median [IQR] = 49 [39.75] vs. 83 [64.55]; P = 0.011), troponin (median [IQR] = 2.13 [1.89] vs. 4.34 [1.99]; P < 0.001), bilirubin (median [IQR] = 0.50 [0.20] vs. 0.40 [0.22]; P < 0.001), and SOFA score (median [IQR] = 2 [2] vs. 5 [2]; P < 0.001) at end of the study compared to the placebo. Also, the time of stay in the hospital (median [IQR] = 5 [1] vs. 6 [3]; P < 0.001) and ICU (median [IQR] = 2.50 [1.00] vs. 3.50 [1.50]; P = 0.002) was lower in the Gln/Arg/HMB group.

CONCLUSION

The present study showed that perioperative supplementation with a combination of Gln, Arg, and HMB enhances the recovery, reduces myocardial injury, and decreases the time of hospital and ICU stay in cardiac surgery patients. These results need to be confirmed in a larger trial.

TRIAL REGISTRATION

IRCT.ir IRCT20120913010826N31. Registered on 13 October 2020.

Crohn's Disease and Female Infertility: Can Nutrition Play a Supporting Role?

Crohn's disease (CD) is a chronic inflammatory disease (IBD) that can affect the entire gastrointestinal tract in a non-continuous mode. CD is generally diagnosed most commonly between 15 and 35 years of age and may affect female fertility. The role of diet in supporting wellbeing outcome and reproductive potential in women is well-known; however, no effective efforts have been made to improve women's awareness in CD. Our review aims to describe the burden of CD on women's fertility, reporting the most relevant nutrients that support reproductive function to ensure women diagnosed with IBD an adequate health-related quality of life.

Vaccines, Microbiota and Immunonutrition: Food for Thought

Vaccines are among the most effective health measures and have contributed to eradicating some diseases. Despite being very effective, response rates are low in some individuals. Different factors have been proposed to explain why some people are not as responsive as others, but what appears to be of critical importance is the presence of a healthy functioning immune system. In this respect, a key factor in modulating the immune system, both in its adaptive and innate components, is the microbiota. While microbiota can be modulated in different ways (i.e., antibiotics, probiotics, prebiotics), an effective and somewhat obvious mechanism is via nutrition. The science of nutrients and their therapeutic application is called immunonutrition, and it is increasingly being considered in several conditions. Our review will focus on the importance of nutrition and microbiota modulation in promoting a healthy immune system while also discussing the overall impact on vaccination response.

The effects of preoperative supplementation with a combination of beta-hydroxy-beta-methylbutyrate, arginine, and glutamine on inflammatory and hematological markers of patients with heart surgery: a randomized controlled trial

Background

Cardiac surgery is associated with a widespread inflammatory response, by an additional release of free radicals. Due to the importance of these patient’s nutritional status, the present study was designed to evaluate the effectiveness of supplementation with a combination of glutamine, β-hydroxy-β-methylbutyrate (HMB) and arginine in patients undergoing to the heart surgery.

Methods

The experiment was performed in 1 month (30 days) before cardiac surgery. patients were asked to take 2 sachets of Heallagen® (a combination of 7 g l-arginine, 7 g l-glutamine, and 1.5 g daily HMB) or placebo with identical appearance and taste (maltodextrin) with 120 cc of water. Clinical and biochemical factors were evaluated in the baseline and end of the study.

Results

Totally, 60 preoperative patients (30 interventions and 30 placeboes) with a mean age of 53.13 ± 14.35 years participated in the study. Subjects in Heallagen® group had a lower serum levels of interleukin-6 (P = 0.023), erythrocyte sedimentation rate (P < 0.01), high sensitivity C-reactive protein (P < 0.01), and lymphocyte number (P = 0.007) compared to the placebo, at end of the study.

Conclusion

In the patients undergoing heart surgery, Heallagen® significantly improved some of the inflammatory factors and hematological parameters. These results need to be confirmed in a larger trial.

Trial registration: The protocol of the study was registered in the IRCT.ir with registration no. IRCT20120913010826N31 at 13/10/2020.

Diet in Intestinal Fibrosis: A Double-Edged Sword

The natural history of inflammatory bowel diseases, especially Crohn’s disease, is frequently complicated by intestinal fibrosis. Because of the lack of effective treatments for intestinal fibrosis, there is an urgent need to develop new therapies. Factors promoting intestinal fibrosis are currently unclear, but diet is a potential culprit. Diet may influence predisposition to develop intestinal fibrosis or alter its natural history by modification of both the host immune response and intestinal microbial composition. Few studies have documented the effects of dietary factors in modulating IBD-induced intestinal fibrosis. As the mechanisms behind fibrogenesis in the gut are believed to be broadly similar to those from extra-intestinal organs, it may be relevant to investigate which dietary components can inhibit or promote fibrosis factors such as myofibroblasts progenitor activation in other fibrotic diseases.

Herbal Medicine and Acupuncture Combined Treatment Attenuates Colitis in Rats

This study aimed to verify the efficacy of a combined treatment of Jakyakgamcho-tang (JGT) and acupuncture (CV12, ST25, CV4) on colitis induced by dextrane sulfate sodium (DSS). Changes in immuno-mediated factors and metabolites were investigated. Colitis symptoms such as body weight loss and elevated disease activity index were alleviated by the combined treatment. Moreover, treatment with JGT and acupuncture restored the disturbed architecture of colon by suppressing inflammatory cytokine levels of IFN-[Formula: see text] ([Formula: see text] < 0.05), IL-5 ([Formula: see text] < 0.05), and IL-13 ([Formula: see text] < 0.0001) compared with the DSS group. Analysis of metabolic profiles of serum revealed that treatment groups were clearly separated from the DSS group, suggesting that JGT and acupuncture treatment altered serum metabolites. Furthermore, treatments caused opposite metabolite patterns for dimethylbenzimidazole, 1,5-anhydro-D-glucitol, proline, phosphate, glycolic acid, aspartic acid, tryptophan, phthalic acid, ornithine, and glutamic acid compared with the DSS group. The combined treatment group induced more effective metabolite patterns than the JGT group, implying that acupuncture treatment can restore metabolic changes caused by DSS induction. These results indicate that the simultaneous treatment of JGT administration and acupuncture procedure provides better management of the immune function and inflammatory expression of colitis than a single treatment. It is assumed that intestinal microbial control can be achieved by acupuncture stimulation as well as by taking herbal medicine.

Can soy isoflavones plus soy protein change serum levels of interlukin-6? A systematic review and meta-analysis of randomized controlled trials

In the present review, we aimed to summarize the effect of soy isoflavones plus soy protein on circulating interlukin-6 (IL-6) in adult participants. Databases including ISI Web of Science, PubMed, Scopus, Cochrane Library, and clinicaltrials.gov were searched up to 23 March 2020. The mean change from baseline of IL-6 concentrations and its SD for intervention and comparison groups were used to calculate the effect size. If the heterogeneity test was statistically significant, DerSimonian and Laird random effects model was used. Cochran's Q test and I-squared statistic were also used to compute the statistical heterogeneity of the intervention's effects. Eighteen studies were known to be eligible for systematic review and 14 studies were selected for meta-analysis. Our meta-analysis results indicated a non-significant effect in serum IL-6 concentrations compared to the comparison group (WMD = 0.03 pg/ml, 95% CI: -0.06, 0.12; p = .459). In subgroup analysis, based on soy isoflavones dosage, it was observed that this combination could reduce IL-6 levels in studies that used isoflavones with dose >84 mg/day (WMD = -0.12 pg/ml 95% CI: -0.24, -0.004; p = .042, I2 = 82.7%) and in articles with a good quality (WMD = -0.15 pg/ml 95% CI: -0.24, -0.05; p = .003, I2 = 62.3%). Performing well-designed intervention studies using a high dose of soy isoflavones is recommended to confirm the beneficial effects of soy ingredients on IL-6.

A 12-month pilot study outcomes of vagus nerve stimulation in Crohn's disease

BACKGROUND

The vagus nerve has anti-inflammatory properties. We aimed to investigate vagus nerve stimulation (VNS) as a new therapeutic strategy targeting an intrinsic anti-inflammatory pathway in a pilot study in Crohn's disease patients. The main objectives addressed the questions of long-term safety, tolerability, and anti-inflammatory effects of this therapy. This study is the continuation of previous reported findings at 6 months.

METHODS

Nine patients with moderate active disease underwent VNS. An electrode wrapped around the left cervical vagus nerve was continuously stimulated over 1 year. Clinical, biological, endoscopic parameters, cytokines (plasma, gut), and mucosal metabolites were followed-up.

KEY RESULTS

After 1 year of VNS, five patients were in clinical remission and six in endoscopic remission. C-reactive protein (CRP) and fecal calprotectin decreased in six and five patients, respectively. Seven patients restored their vagal tone and decreased their digestive pain score. The patients' cytokinergic profile evolved toward a more "healthy profile": Interleukins 6, 23, 12, tumor necrosis factor α, and transforming growth factorβ1 were the most impacted cytokines. Correlations were observed between CRP and tumor necrosis factor α, and some gut mucosa metabolites as taurine, lactate, alanine, and beta-hydroxybutyrate. VNS was well tolerated.

CONCLUSION & INFERENCES

Vagus nerve stimulation appears as an innovative and well-tolerated treatment in moderate Crohn's disease. After 12 months, VNS has restored a homeostatic vagal tone and reduced the inflammatory state of the patients. VNS has probably a global modulatory effect on the immune system along with gut metabolic regulations. This pilot study needs replication in a larger randomized double-blinded control study.

Mast Cell Regulation and Irritable Bowel Syndrome: Effects of Food Components with Potential Nutraceutical Use

Mast cells are key actors in inflammatory reactions. Upon activation, they release histamine, heparin and nerve growth factor, among many other mediators that modulate immune response and neuron sensitization. One important feature of mast cells is that their population is usually increased in animal models and biopsies from patients with irritable bowel syndrome (IBS). Therefore, mast cells and mast cell mediators are regarded as key components in IBS pathophysiology. IBS is a common functional gastrointestinal disorder affecting the quality of life of up to 20% of the population worldwide. It is characterized by abdominal pain and altered bowel habits, with heterogeneous phenotypes ranging from constipation to diarrhea, with a mixed subtype and even an unclassified form. Nutrient intake is one of the triggering factors of IBS. In this respect, certain components of the daily food, such as fatty acids, amino acids or plant-derived substances like flavonoids, have been described to modulate mast cells' activity. In this review, we will focus on the effect of these molecules, either stimulatory or inhibitory, on mast cell degranulation, looking for a nutraceutical capable of decreasing IBS symptoms.

Oxidative Stress and Redox-Modulating Therapeutics in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is associated with the production of reactive species that target cysteine redox switches in proteins, thereby affecting gene regulation, DNA damage, ion transport, intermediary metabolism, and mitochondrial function. Precursors of reactive species are derived from organic and inorganic compounds and their cofactors, including amino acids, vitamins, oxygen, nitrite, and sulfate. Nutrition and the gut microbiome fuel this process to a significant extent. The production of reactive species in IBD is reflected by a reduction in systemic free thiols, the major components of the antioxidant machinery. Systemic free thiols are amenable to nutritional or therapeutic intervention. This opens up future avenues for therapeutic modulation of redox status in IBD.

L-arginine effect on inflammatory mediators: A systematic review of randomized controlled clinical trials

L-arginine is an important factor in several physiological and biochemical processes. Recently, scientists studied L-arginine effect on inflammatory mediators such as C-reactive protein (CRP), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). We conducted a systematic review on randomized controlled trials assessing L-arginine effect on inflammatory mediators. We searched data bases including Google scholar, ISI web of science, SCOPUS, and PubMed/Medline up to April 2019. Randomized clinical trials assessing the effect of L-arginine on inflammatory mediators in human adults were included. Our search retrieved eleven articles with 387 participants. Five articles were on patients with cancer and 6 articles were on adults without cancer. L-arginine was applied in enteral form in 5 articles and in oral form in 6 articles. Eight articles were on both genders, two articles were on women, and one article was on men. L-arginine could not reduce inflammatory mediators among patients with and without cancer except one article which indicated that taking L-arginine for 6 months decreased IL-6 among cardiopathic nondiabetic patients. Our results indicated that L-arginine might not be able to reduce selected inflammatory mediators, but for making a firm decision more studies are needed to be conducted with longer intervention duration, separately on male and female and with different doses of L-arginine.

Effect of pre- and post-weaning dietary supplementation with arginine and glutamine on rabbit performance and intestinal health

BACKGROUND

The purpose of the present study was to assess if the exposure to glutamine (Gln), arginine (Arg) or their combination from pregnancy, through the maternal diet, to a post weaning supplemented diet, can stimulate litter performance, gut development and immune function. To this end does and their litters were fed the same basal diet no supplemented (control C), or supplemented with 0.4% Gln, 0.4% Arg, or 0.4 Gln + 0.4 Arg. Rabbits were weaned at 25 d of age and fed the same experimental diet as their mothers for 10 additional days (35 d of age). Bacterial translocation to mesenteric lymph nodes (MLN) at 6 d of age and intestinal histology, enzymatic activity, phenotypical and functional analysis of intraepithelial lymphocytes (IEL) from the appendix were determined at 6, 25 and 35 d of age.

RESULTS

No significant differences on animal performance or mortality rates were observed among dietary treatments. However, kits from rabbit does supplemented with Gln tended (P ≤ 0.10) to reduce the translocation of total number of both aerobic and facultative anaerobic bacteria to the MLN. Also, rabbits fed the Gln supplemented diets maintained intestinal villous height at weaning compared to the non-supplemented diets (P < 0.05). The proportions of CD45+CD4+ and CD45+CD8+ IEL in the appendix were not affected by dietary means. However, in rabbits IEL at weaning dietary Gln significantly upregulated IL-2 and downregulated IL-6 expression.

CONCLUSIONS

Despite a lack of effect on performance and mortality the inclusion of 0.4% Gln has a positive effect by maintaining intestinal villous height and modulating the cytokine profile at weaning. The supplementation with Arg or Arg + Gln at the selected doses in this study did not exert positive effects on rabbit intestinal health.

Apoptosis perturbations and expression of regulatory inflammatory factors in cisplatin-depleted rat livers under l-arginine protection

Hepatic injury is one of the most common complications associated with cisplatin (CIS) use. Recently, liver protection lines are being discovered to stop the hepatic cell death due to inflammatory and apoptotic perturbations. l-arginine has protective effects in several models of liver injury. This study was designed to investigate the possible protective effect of l-arginine against CIS-induced acute hepatic injury in rats. Rats were divided into 4 groups: control, l-arginine, CIS, l-arginine + CIS. Liver function, oxidative stress, inflammatory cytokines, and apoptosis markers were assessed. l-arginine pretreatment protected the liver against CIS-induced toxicity as indicated by significantly alleviating the changes in liver function along with restoration of the antioxidant status. This finding was confirmed with the markedly improved pathological changes. l-arginine showed anti-inflammatory effect through the reduction of liver expression of iNOS, TNF-α, and NF-κβ, which were ameliorated to significant levels. Furthermore, l-arginine administration downregulated the liver expression of the apoptotic marker, caspase-3. The results recommend l-arginine as a hepatoprotective agent against CIS toxicity. Mostly, this hepatoprotective effect of l-arginine involved anti-inflammatory and anti-apoptotic activities.

Integration of multi-omics data and deep phenotyping enables prediction of cytokine responses

The immune response to pathogens varies substantially among people. While both genetic and non-genetic factors contribute to inter-person variation, their relative contributions and potential predictive power have remained largely unknown. By systematically correlating host factors in 534 healthy volunteers, including baseline immunological parameters and molecular profiles (genome, metabolome and gut microbiome), with cytokine-production capacity after stimulation with 20 pathogens, we identified distinct patterns of co-regulation. Among the 91 different cytokine–stimulus pairs, 11 categories of host factors together explained up to 67% of inter-individual variation in cytokine production induced by stimulation. A computational model based on genetic data predicted the genetic component of stimulus-induced cytokine-production (correlation 0.28-0.89), while non-genetic factors influenced cytokine production as well.

Functions and Signaling Pathways of Amino Acids in Intestinal Inflammation

Intestine is always exposed to external environment and intestinal microorganism; thus it is more sensitive to dysfunction and dysbiosis, leading to intestinal inflammation, such as inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and diarrhea. An increasing number of studies indicate that dietary amino acids play significant roles in preventing and treating intestinal inflammation. The review aims to summarize the functions and signaling mechanisms of amino acids in intestinal inflammation. Amino acids, including essential amino acids (EAAs), conditionally essential amino acids (CEAAs), and nonessential amino acids (NEAAs), improve the functions of intestinal barrier and expressions of anti-inflammatory cytokines and tight junction proteins but decrease oxidative stress and the apoptosis of enterocytes as well as the expressions of proinflammatory cytokines in the intestinal inflammation. The functions of amino acids are associated with various signaling pathways, including mechanistic target of rapamycin (mTOR), inducible nitric oxide synthase (iNOS), calcium-sensing receptor (CaSR), nuclear factor-kappa-B (NF-κB), mitogen-activated protein kinase (MAPK), nuclear erythroid-related factor 2 (Nrf2), general controlled nonrepressed kinase 2 (GCN2), and angiotensin-converting enzyme 2 (ACE2).

Alterations of oxygen consumption and extracellular acidification rates by glutamine in PBMCs of SLE patients

We evaluated plasma glutamine levels and basal mitochondrial oxygen consumption rate (mOCR_B) and basal extracellular acidification rate (ECAR_B) of peripheral blood mononuclear cells (PBMCs) of systemic lupus erythematous (SLE) patients and healthy controls (HCs). Lower plasma glutamine levels correlated with higher SLE disease activity indexes (p=0.025). Incubated in DMEM containing 100mg/dL glucose, SLE-PBMCs displayed lower mOCR_B (p=0.018) but similar ECAR_B (p=0.467) to those of HC-PBMCs, and their mOCR_B got elevated (p<0.001) without altering ECAR_B (p=0.239) by supplementation with 2 or 4mM glutamine. We conclude that impaired mitochondrial respiration of SLE-PBMCs could be improved by glutamine under euglycemic condition.

Plasma-Free Amino Acid Profiles in Crohn's Disease: Relationship With the Crohn Disease Activity Index

We aimed to clarify the relationship between plasma-free amino acid (PFAA) profiles and the Crohn's disease (CD) activity index (CDAI) in patients with CD.

METHODS

We measured fasting PFAA concentrations in 29 patients with CD and their correlation with disease activity.

RESULTS

In all patients, significant correlations were noted between CDAI and concentrations of valine, methionine, leucine, histidine, tryptophan, alanine, tyrosine, total amino acids (TAAs), nonessential amino acids (NEAAs), essential amino acids (EAAs), and branched-chain amino acids (BCAAs). In patients with the ileo-colonic type of CD, significant correlations were noted between CDAI and valine, histidine, tryptophan, glutamine, TAA, NEAA, EAA, and BCAA. In ileal type, significant correlations were observed between CDAI and threonine, valine, histidine, serine, and glycine. In colonic type, significant correlations were noted between CDAI and valine, histidine, tryptophan, TAA, NEAA, EAA, and BCAA.

CONCLUSIONS

In patients with CD, plasma amino acids appear to be associated with disease activity.

Therapeutic Potential of Amino Acids in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), which includes both ulcerative colitis and Crohn’s disease, is a chronic relapsing inflammation of the gastrointestinal tract, and is difficult to treat. The pathophysiology of IBD is multifactorial and not completely understood, but genetic components, dysregulated immune responses, oxidative stress, and inflammatory mediators are known to be involved. Animal models of IBD can be chemically induced, and are used to study etiology and to evaluate potential treatments of IBD. Currently available IBD treatments can decrease the duration of active disease but because of their adverse effects, the search for novel therapeutic strategies that can restore intestinal homeostasis continues. This review summarizes and discusses what is currently known of the effects of amino acids on the reduction of inflammation, oxidative stress, and cell death in the gut when IBD is present. Recent studies in animal models have identified dietary amino acids that improve IBD, but amino acid supplementation may not be adequate to replace conventional therapy. The animal models used in dietary amino acid research in IBD are described.

L-arginine attenuates Interleukin-1β (IL-1β) induced Nuclear Factor Kappa-Beta (NF-κB) activation in Caco-2 cells

Background

Specific nutrients like L-arginine (L-Arg) ameliorate intestinal inflammation, however the exact mechanisms of this effect are unclear. We hypothesized the anti-inflammatory effects of L-Arg require active transport and metabolism by inducible nitric oxide synthase (iNOS) to generate nitric oxide (NO). To test this hypothesis we examined the effects of L-Arg, L-Arg transport activity, NO production and iNOS inhibitor on IL-1β-mediated NF-κB-activation in Caco-2 cells.

Methods

Caco-2 cells were cultured, transfected with a NF-κB promoter luciferase vector, incubated ± L-Arg, ± IL-1β and luciferase activity was measured. Using siRNA we inhibited the L-Arg cationic amino acid transporter system y⁺ (CAT1) expression and examined its effects on L-Arg transport activity and IL-1β-mediated NF-κB-activation. Finally, the effects of sodium nitroprusside (SNP, a NO donor) and Nω-nitro-L-arginine (NNA, an iNOS inhibitor) on IL-1β-mediated NF-κB-activation were examined.

Results

IL-1β increased NF-κB luciferase activity (8-fold) and NF-κB expression (mRNA and protein), both of these were significantly decreased by L-Arg. System y⁺ CAT1 siRNA decreased CAT1 expression, L-Arg transport activity and attenuated the inhibitory effects of L-Arg on NF- κB activity. SNP attenuated the IL-1β-induced increase in NF-κB luciferase activity and expression, whereas NNA diminished the inhibitory effects of L-Arg on IL-1β-inducible NF- κB luciferase activity.

Conclusion

The inhibitory effects of L-Arg on IL-1β-mediated NF-κB-activation in Caco-2 cells involve L-Arg transport activity by CAT1, regulation of IL-1β-mediated increases in NF-κB expression, changes in iNOS expression and NO production. Our data suggest the inhibitory effects of L-Arg on NF-κB activation are mediated in part by iNOS since SNP preserves and NNA attenuates the effects of L-Arg on IL-1β-mediated NF-κB-activation and expression.

Exploring and Enhancing the Anti-Inflammatory Properties of Polymeric Formula

BACKGROUND

Exclusive enteral nutrition (EEN) therapy using a polymeric formula (PF) can substantially attenuate intestinal inflammation in Crohn's disease (CD) patients. However, the mechanism(s) by which EEN suppresses inflammation are not yet fully understood. The aims were to examine cellular mechanism(s) through which EEN may suppress inflammation and investigate potential pathways to enhance anti-inflammatory properties of EEN.

METHODS

Glutamine, arginine, vitamin D3, and α linolenic acid (ALA), present in PF, along with curcumin, were identified as immunoactive nutrient therapies. Tumor necrosis factor (TNF)-α-exposed HT-29 colonic epithelial cells were used to investigate the immunosuppressive activity of the nutrients by assessing their effect on cell viability, cell activity, chemokine response (interleukin-8 [IL-8]), nuclear factor (NF)-κB, P38 mitogen-activated protein kinase, IκB kinase (Iκκ), and nitric oxide (NO).

RESULTS

Cellular viability and activity were maintained with all nutrient treatments. Glutamine, arginine, and vitamin D3, but not ALA, significantly attenuated IL-8 production. Glutamine and arginine led to phosphorylation blockade of the signaling components in NF-κB and P38 pathways, reduction in kinase activity, and enhancement in NO production. Combining glutamine, arginine, and curcumin at optimal concentrations completely abolished the IL-8 response.

CONCLUSIONS

These data indicate that glutamine, arginine, and vitamin D3 can suppress inflammation at concentrations equivalent to those used in PF. The mechanisms of this action were mediated through influencing the NF-κB and P38 cascades. Glutamine and arginine-fortified PF with curcumin might be a promising option to enhance the effectiveness and expand the scope of EEN therapy in CD treatment.

Divergent Relationships between Fecal Microbiota and Metabolome following Distinct Antibiotic-Induced Disruptions

Despite the fundamental importance of antibiotic therapies to human health, their functional impact on the intestinal microbiome and its subsequent ability to recover are poorly understood. Much research in this area has focused on changes in microbiota composition, despite the interdependency and overlapping functions of many members of the microbial community. These relationships make prediction of the functional impact of microbiota-level changes difficult, while analyses based on the metabolome alone provide relatively little insight into the taxon-level changes that underpin changes in metabolite levels. Here, we used combined microbiota and metabolome profiling to characterize changes associated with clinically important antibiotic combinations with distinct effects on the gut. Correlation analysis of changes in the metabolome and microbiota indicate that a combined approach will be essential for a mechanistic understanding of the functional impact of distinct antibiotic classes.

The intestinal microbiome plays an essential role in regulating many aspects of host physiology, and its disruption through antibiotic exposure has been implicated in the development of a range of serious pathologies. The complex metabolic relationships that exist between members of the intestinal microbiota and the potential redundancy in functional pathways mean that an integrative analysis of changes in both structure and function are needed to understand the impact of antibiotic exposure. We used a combination of next-generation sequencing and nuclear magnetic resonance (NMR) metabolomics to characterize the effects of two clinically important antibiotic treatments, ciprofloxacin and vancomycin-imipenem, on the intestinal microbiomes of female C57BL/6 mice. This assessment was performed longitudinally and encompassed both antibiotic challenge and subsequent microbiome reestablishment. Both antibiotic treatments significantly altered the microbiota and metabolite compositions of fecal pellets during challenge and recovery. Spearman’s correlation analysis of microbiota and NMR data revealed that, while some metabolites could be correlated with individual operational taxonomic units (OTUs), frequently multiple OTUs were associated with a significant change in a given metabolite. Furthermore, one metabolite, arginine, can be associated with increases/decreases in different sets of OTUs under differing conditions. Taken together, these findings indicate that reliance on shifts in one data set alone will generate an incomplete picture of the functional effect of antibiotic intervention. A full mechanistic understanding will require knowledge of the baseline microbiota composition, combined with both a comparison and an integration of microbiota, metabolomics, and phenotypic data.

IMPORTANCE Despite the fundamental importance of antibiotic therapies to human health, their functional impact on the intestinal microbiome and its subsequent ability to recover are poorly understood. Much research in this area has focused on changes in microbiota composition, despite the interdependency and overlapping functions of many members of the microbial community. These relationships make prediction of the functional impact of microbiota-level changes difficult, while analyses based on the metabolome alone provide relatively little insight into the taxon-level changes that underpin changes in metabolite levels. Here, we used combined microbiota and metabolome profiling to characterize changes associated with clinically important antibiotic combinations with distinct effects on the gut. Correlation analysis of changes in the metabolome and microbiota indicate that a combined approach will be essential for a mechanistic understanding of the functional impact of distinct antibiotic classes.

IBD: In Food We Trust

BACKGROUND AND AIMS

Both science and patients associate diet with inflammatory bowel disease [IBD]. There is no doubt that links between IBD and diet are numerous, based on both epidemiological studies and experimental studies. However, scientific evidence to support dietary advice is currently lacking, and dietary counselling for IBD patients is often limited in clinical practice to the improvement of nutrient intake. This review aimed to focus on both patient's beliefs about and molecular mechanisms for crosstalk between nutrients and inflammation.

METHODS

A literature search using PubMed was performed to identify relevant studies on diet and/or nutrients and their role in IBD. Pubmed [from inception to January 20, 2016] was searched using the terms: 'Crohn', 'colitis',' intestinal epithelial cells', and a list of terms relating to diet or numerous specific nutrients. Terms associated with nutrients were individually tested in the context of IBD. Reference lists from studies selected were manually searched to identify further relevant reports. Manuscripts about diet in the context of IBD from basic science, epidemiological studies, or clinical trials were selected and reviewed. Only articles published in English were included.

RESULTS

Epidemiological studies highlight the key role of diet in IBD development, and many IBD patients report diet as a triggering factor in relapse of disease. In addition, we present research on the impact of nutrients on innate immunity.

CONCLUSION

Diet may offer an alternative approach to restoring deficient innate immunity in IBD, and this may be the scientific rationale for providing dietary counselling for IBD patients.

A phase III study evaluating oral glutamine and transforming growth factor-beta 2 on chemotherapy-induced toxicity in patients with digestive neoplasm

BACKGROUND

Patients with gastrointestinal (GI) cancer are exposed to cachexia, which is highly correlated with chemotherapy-induced side effects. Research suggests that specific immunonutrients could prevent such toxicities.

AIMS

The primary objective of this phase III study was to evaluate the efficacy of glutamine and transforming growth factor-β2 (TGF-β2) in the prevention of grade 3-4 non-hematological toxicities induced by chemotherapy in patients with GI cancer.

PATIENTS AND METHODS

We designed a double-blind, randomized, controlled and multicenter trial stratified according to center, type of chemotherapy, presence of cachexia, and age. Patients were randomized to receive either Clinutren Protect(®) (CP) or a control isocaloric diet (without TGF-β2 or glutamine).

RESULTS

Between November 2007 and October 2011, 210 patients were enrolled in the study, of which 201 were included in the intention-to-treat analysis. Grade 3-4 non-hematological toxicities were not significantly different between the CP and control groups when evaluated by univariate and multivariate analyses. Likewise, no difference was observed regarding grade 3-4 hematological toxicities or reasons for treatment interruption.

CONCLUSION

This randomized study does not support the hypothesis that oral glutamine and TGF-β2 supplementation is effective to reduce grade 3 or 4 non-hematological toxicities induced by chemotherapy in patients with GI neoplasm.

Advances in nutritional therapy in inflammatory bowel diseases: Review

Inflammatory bowel diseases (IBD), including ulcerative colitis and Crohn's disease are chronic, life-long, and relapsing diseases of the gastrointestinal tract. Currently, there are no complete cure possibilities, but combined pharmacological and nutritional therapy may induce remission of the disease. Malnutrition and specific nutritional deficiencies are frequent among IBD patients, so the majority of them need nutritional treatment, which not only improves the state of nutrition of the patients but has strong anti-inflammatory activity as well. Moreover, some nutrients, from early stages of life are suspected as triggering factors in the etiopathogenesis of IBD. Both parenteral and enteral nutrition is used in IBD therapy, but their practical utility in different populations and in different countries is not clearly established, and there are sometimes conflicting theories concerning the role of nutrition in IBD. This review presents the actual data from research studies on the influence of nutrition on the etiopathogenesis of IBD and the latest findings regarding its mechanisms of action. The use of both parenteral and enteral nutrition as therapeutic methods in induction and maintenance therapy in IBD treatment is also extensively discussed. Comparison of the latest research data, scientific theories concerning the role of nutrition in IBD, and different opinions about them are also presented and discussed. Additionally, some potential future perspectives for nutritional therapy are highlighted.

Identifying the immunomodulatory components of helminths

Immunomodulatory components of helminths offer great promise as an entirely new class of biologics for the treatment of inflammatory diseases. Here, we discuss the emerging themes in helminth-driven immunomodulation in the context of therapeutic drug discovery. We broadly define the approaches that are currently applied by researchers to identify these helminth molecules, highlighting key areas of potential exploitation that have been mostly neglected thus far, notably small molecules. Finally, we propose that the investigation of immunomodulatory compounds will enable the translation of current and future research efforts into potential treatments for autoimmune and allergic diseases, while at the same time yielding new insights into the molecular interface of host-parasite biology.

Dietary saturated fatty acids reduce hepatic lipid accumulation but induce fibrotic change in alcohol-fed rats

BACKGROUND

In this study, we evaluated the influence of an ethanol-containing diet with high saturated fatty acids (SFAs) on alcoholic liver disease (ALD) in rats.

METHODS

Male Wistar rats weighing about 160 g were divided into four groups: an ethanol (E) group fed an ethanol-containing liquid diet with 36% total calories as fat (corn oil, olive oil and safflower oil); a control (C) group pair-fed an isoenergetic diet without ethanol; an ethanol with saturated fat (EHS) group fed an ethanol-containing diet which contained 40% total calories as fat (90% lard); and a control with saturated fat (CHS) group fed an isoenergetic diet without ethanol, which contained 40% total calories as fat.

RESULTS

After 8 weeks of treatment, the liver weight and plasma aspartate aminotransferase (AST) activities in E and EHS groups were significantly higher than those of C group. Significantly higher scores of inflammation, necrosis, and fatty changes were found in E group, whereas significantly higher scores of necrosis, bile duct hyperplasia, and fibrosis were found in EHS group. Although significantly lower plasma adiponectin concentrations were observed in both E and EHS groups, compared to C group, plasma adiponectin in EHS group was significantly higher than that in E group. There was no change in hepatic peroxisome proliferator activated receptor (PPAR)-α expression between E and C groups, and rats in EHS group showed a significantly elevated level compared to the other groups. A lower hepatic sirtuins (SIRT)-1 level was found in E group, but it did not reach statistical significance. Moreover, the highest plasma TGF-β1 level was found in EHS group. Compared to C group, the hepatic reduced glutathione/oxidized glutathione ratio and thiobarbituric acid (TBA)-reactive substance level were significantly increased in E and EHS groups; however, there was no significant difference between E and EHS groups. Significantly increased hepatic CYP2E1 expression was observed in both E and EHS groups, while at the same time, hepatic CYP2E1 in EHS group was the highest among all groups. The hepatic tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6, and IL-10 concentrations in the E group were significantly higher than those in C group, whereas the hepatic IL-6 and IL-10 concentrations in ES group were significantly lower than those of E group.

CONCLUSIONS

These results suggested that dietary saturated fats may inhibit hepatic fat accumulation and induce hepatic fibrosis in rats under chronic alcohol intake.

L-arginine and aminoguanidine reduce colonic damage of acetic acid-induced colitis in rats: potential modulation of nuclear factor-κB/p65

The transcription factor, nuclear factor-κB (NF-κB) is a key inducer of inducible nitric oxide synthase (iNOS) gene expression. The aim of the present study was to investigate the potential protective effect of l-arginine (Arg; nitric oxide precursor) and aminoguanidine (inducible nitric oxide synthase inhibitor) against acetic acid (AA)-induced colitis in rats, and the potential role of NF-κB. Colitis was induced by intrarectal inoculation of rats with 4% acetic acid for three consecutive days. The effect of Arg and aminoguanidine on nitric oxide levels was assessed by Greiss assay and protein expression of NF-κB/p65, and inducible nitric oxide synthase was also investigated by immunohistochemistry. Slides were examined using ImageJ, and results reported as the percent area positive for each marker. Intrarectal AA caused a significant increase in bodyweight loss and colon weights. Arg at 100 mg/day for 7 days before induction of colitis diminished the changes in both bodyweight loss and colon weights. Furthermore, Arg attenuated the colonic tissues macroscopic and microscopic damage induced by acetic acid. In addition, i.p. AG 100 mg/kg given during and after induction of colitis recovered the colonic ulcerative lesion induced by AA. Arg can protect against colonic inflammation; an effect that probably be attributed to its nitric oxide-donating property, resulting in modulatory effects on the expression of NF-κB/p65 in the colon tissues. The results suggested that Arg might reduce the inflammation associated with colitis as confirmed by histopathological investigations. Arg might inhibit AA-induced colitis through the NF-κB/nitric oxide pathway.

Rapid determination of glutamine in human plasma by high-performance liquid chromatographic-tandem mass spectrometry and its application in pharmacokinetic studies

A rapid and accurate high-performance liquid chromatographic-tandem mass spectrometric method was developed and validated for the determination of glutamine in human plasma. Phenomenex EZ: faast(TM) amino acid analysis kit was used for sample pretreatment. Chromatographic separation was conducted on an EZ: faast amino acid analysis-mass spectrometry column (250 × 3.0 mm i.d., 4 μm). A binary gradient elution of mobile phases A (0.2% formic acid containing 5 mM ammonium acetate) and B (methanol, containing 0.2% formic acid and 5 mM ammonium acetate) was programmed at 0.4 mL/min. Multiple reaction monitoring was used for quantification by monitoring ion transitions of m/z 275.3/172.1 for derivatized glutamine and 317.3/84.1 for internal standard in the electrospray positive ionization mode. The standard curve was linear (r(2) > 0.99) over the concentration range of 3.14-157.20 μg/mL. The intra- and inter-day precision values were <8.70% and the accuracy within -4.35 to 8.91% at three concentrations. The method was successfully applied to the pharmacokinetic study in Chinese healthy male subjects following oral administration of glutamine with doses of 2 and 4 g.

The protective effect of VSL#3 on intestinal permeability in a rat model of alcoholic intestinal injury

Background

This study aimed to investigate the mechanism of the probiotic VSL#3 in acute alcoholic intestinal injury, and evaluate the effect of VSL#3, glutamine,VSL#3+glutamine and heat-killed VSL#3 therapy in a rat model.

Methods

Six- to eight-week-old male wild-type rats were divided into seven groups. To establish the acute alcohol liver disease model, rats received three doses of corn starch dissolved in PBS/40% alcohol administered intra-gastrically every 12 hours. Treatment groups received an intra-gastric dose of VSL#3, Glutamine, heat-killed VSL#3, or VSL#3+Glutamine 30 minutes prior to alcohol administration. The placebo group was treated with PBS prior to alcohol administration. TNFα and endotoxin in plasma was measured by ELISA and Tachypleus Ameboctye Lysate assays, and electron microscopy, Western blotting, and reverse transcription polymerase chain reaction were used to identify the mechanisms of VSL#3 in the regulation of epithelial permeability.

Results

First, compared with control group, endotoxin and TNFα in alcohol group was obviously high. At the same time, in VSL#3 group,the expression of endotoxin and TNFα obviously lower than the alcohol group. And the trends of the expression of tight junction proteins in these groups were reversed with the change of endotoxin and TNFα. Second, compared the groups of VSL#3 with glutamine,VSL#3+glutamine and heat-killed VSL#3,we found that both VSL#3 and heat-killed VSL#3, glutamine were as effective as VSL#3+glutamine in the treatment of acute alcohol liver disease, the expression of endotoxin and TNFα were lower than the alcohol group, and tight junction proteins were higher than the alcohol group whereas the expression of tight junction proteins were higher in VSL#3 + glutamine group than either agent alone, but have no significant difference.

Conclusion

We conclude that VSL#3 treatment can regulate the ecological balance of the gut microflora, preventing passage of endotoxin and other bacterial products from the gut lumen into the portal circulation and down-regulating the expression of TNFα, which could otherwise down-regulate the expression of tight junction proteins and increase epithelial permeability.

Dietary protein excess during neonatal life alters colonic microbiota and mucosal response to inflammatory mediators later in life in female pigs

The interplay between the colonic microbiota and gut epithelial and immune cells during the neonatal period, which establishes the structure of the microbiota and programs mucosal immunity, is affected by the diet. We hypothesized that protein-enriched milk formula would disturb this interplay through greater flux of protein entering the colon, with consequences later in life. Piglets were fed from postnatal day (PND) 2 to 28 either a normal-protein formula (NP; 51 g protein/L) or high-protein formula (HP; 77 g protein/L) and weaned at PND28, when they received standard diets until PND160. HP feeding transiently increased the quantity of protein entering the colon (PND7) but did not change the microbiota composition at PND28, except for a higher production of branched-chain fatty acids (BCFAs) in an in vitro fermentation test (P < 0.05). HP piglets had greater colonic mucosa densities of cluster of differentiation (CD) 3(+) and CD172(+) cells and lower Il-1β and Tnfα mRNA levels at PND28 (P < 0.05). Later in life (PND160), HP females, but not males, had a higher increase in colonic permeability after ex vivo oxidative stress and higher cytokine secretion in response to lipopolysaccharide in colonic explant cultures than NP females (P < 0.05). HP females also had lower colonic amounts of F. prausnitzii and BCFAs (P < 0.05). BCFAs displayed a dose-dependent protection against inflammation-induced alteration of barrier function in Caco-2 cells (P < 0.05). In conclusion, protein-enriched formula had little impact on colonic microbiota, but it modified colonic immune cell development and had a long-term effect on adult colonic mucosa sensitivity to inflammatory insults, probably through microbiotal and hormonal factors.

Effects of dietary arginine and glutamine on alleviating the impairment induced by deoxynivalenol stress and immune relevant cytokines in growing pigs

Deoxynivalenol (DON) is a mycotoxin that reduces feed intake and animal performance, especially in swine. Arginine and glutamine play important roles in swine nutrition. The objective of this study was to determine the effects of dietary supplementation with arginine and glutamine on both the impairment induced by DON stress and immune relevant cytokines in growing pigs. A total of forty 60-d-old healthy growing pigs with a mean body weight of 16.28±1.54 kg were randomly divided into 5 groups, and assigned to 3 amino acid treatments fed 1.0% arginine (Arg), 1.0% glutamine (Gln) and 0.5% Arg+0.5% Gln, respectively, plus a toxin control and a non-toxin control. Pigs in the 3 amino acid treatments were fed the corresponding amino acids, and those in non-toxin control and toxin control were fed commercial diet with 1.64% Alanine as isonitrogenous control for 7 days. The toxin control and amino acid treatments were then challenged by feeding DON-contaminated diet with a final DON concentration of 6 mg/kg of diet for 21 days. No significant differences were observed between toxin control and the amino acid groups with regard to the average daily gain (ADG), although the values for average daily feed intake (ADFI) in the amino acid groups were significantly higher than that in toxin control (P<0.01). The relative liver weight in toxin control was significantly greater than those in non-toxin control, arginine and Arg+Glu groups (P<0.01), but there were no significant differences in other organs. With regard to serum biochemistry, the values of BUN, ALP, ALT and AST in the amino acid groups were lower than those in toxin control. IGF1, GH and SOD in the amino acid groups were significantly higher than those in toxin control (P<0.01). The IL-2 and TNFα values in the amino acid groups were similar to those in non-toxin control, and significantly lower than those in toxin control (P<0.01). These results showed the effects of dietary supplementation with arginine and glutamine on alleviating the impairment induced by DON stress and immune relevant cytokines in growing pigs.

Glutamine on Intestinal Inflammation: A Mechanistic Perspective

Intestinal inflammation is associated with various pathological diseases, such as gastritis from Helicobacter pylori infection, Crohn's and colitis in inflammatory bowel disease, and colorectal cancer. Thus, treatment with anti-inflammatory substances in these inflammation-associated diseases is critical. Increasingly compelling evidence indicates that glutamine is an anti-inflammatory compound candidate because it can influence the long-term outcome of the inflammatory diseases with in a low-risk way. However, before recommending its use in clinical practice, it is important to elucidate the molecular mechanism by which glutamine exerts its roles in modulating intestinal inflammation. In this study, we review the current knowledge on the detailed regulation pathway used by glutamine in its proinflammatory regulation, with a special emphasis on intestinal inflammation. These regulation pathways include nuclear factor kappa B (NF-κB), signal transducer and activator of transcription (STAT), mitogen-activated protein kinases (MAPK), phosphoinositide-3-kinases (PI3K)/PI3K-protein kinase B (Akt), activating protein-1 (AP-1), nitric oxide synthases (NOS)-nitric oxide (NO), peroxisome proliferator-activated receptor-Γ (PPARγ), heat shock factor-1 (HSF-1)- heat shock proteins (HSP) and glutathione (GSH) - reactive oxygen species (ROS). Although some regulatory pathways, such as PI3K/PI3K-Akt, GSH-ROS and AP-1, need to be further investigated, this review provides useful information to utilize glutamine as an immunonutritional or pharmaconutritional drug, not only for inflammation-associated diseases in the intestine, but also possibly for other inflammatory-associated diseases, i.e. arthritis, asthma, type 2 diabetes, etc.

Glutamine and alanine-induced differential expression of intracellular IL-6, IL-8, and TNF-α in LPS-stimulated monocytes in human whole-blood

To investigate the effects of the commonly-used immunomodulators l-glutamine, l-alanine, and the combination of both l-alanyl-l-glutamine (Dipeptamin(®)) on intracellular expression of IL-6, IL-8, and TNF-α during endotoxemia, lipopolysaccharide (LPS)-stimulated human monocytes in a whole blood system were investigated by flow cytometry. Whole blood of twenty-seven healthy volunteers was stimulated with LPS and incubated with three different amino acid solutions (1. l-glutamine, 2. l-alanine, 3. l-alanyl-l-glutamine, each concentration 2 mM, 5 mM, incubation time 3 h). CD14(+) monocytes were phenotyped in whole-blood and intracellular expression of cytokines was assessed by flow cytometry. Our investigations showed for the first time in whole blood probes, imitating best physiologically present cellular interactions, that l-glutamine caused a dose-independent inhibitory effect on IL-6 and TNF-α production in human monocytes stimulated with LPS. However, l-alanine had contrary effects on IL-6 expression, significantly upregulating expression of IL-6 in LPS-treated monocytes. The impact of l-alanine on the expression of TNF-α was comparable with glutamine. Neither amino acid was able to affect IL-8 production in LPS-stimulated monocytes. The combination of both did not influence significantly IL-6 and IL-8 expression in monocytes during endotoxemia, however strongly reduced TNF-α production. For the regulation of TNF-α, l-glutamine, l-alanine and the combination of both show a congruent and exponentiated downregulating effect during endotoxemia, for the modulation of IL-6, l-glutamine and l-alanine featured opposite regulation leading to a canceling impact of each other when recombining both amino acids.

Chemopreventive effect of dietary glutamine on colitis-associated colon tumorigenesis in mice

Chronic colonic inflammation is a known risk factor for colorectal cancer (CRC). Glutamine (GLN) supplementation has shown its anti-inflammation benefit in experimental colitis. Whether GLN is effective in preventing colon carcinogenesis remains to be investigated. The chemopreventive activity of GLN was evaluated in the mouse model of dextran sulfate sodium (DSS)/azoxymethane (AOM)-induced colitis-associated CRC in this study. Mice were treated with DSS/AOM and randomized to receive either a control diet or GLN-enriched diet intermittently of the study. The disease activity index was evaluated weekly. On day 80 of the experiment, the entire colon and rectum were processed for histopathologic examination and further evaluation. Pro-inflammatory mediators and cytokines were measured by enzyme-linked immunosorbent assay, real-time-PCR and western blot analysis. Here, we show that after GLN-enriched diet, the colitis presented a statistical improvement and tumors burden decreased significantly. This was accompanied by lower activity of nuclear factor-κB (NF-κB), decreased expression of cyclooxygenase-2 and inducible nitric oxide synthase, lower expression of cytokines and chemokines as well as reduced proliferation and induced apoptosis in the colons of colitis-associated CRC mice. Our data demonstrate the protective/preventive effect of GLN in the progression of colitis-associated CRC, which was correlated with a dampening of inflammation and NF-κB activity and with a decrease of inflammatory protein overexpression.

Role of toll like receptors in irritable bowel syndrome: differential mucosal immune activation according to the disease subtype

Background

The irritable bowel syndrome (IBS) is a functional gastrointestinal disorder whose pathogenesis is not completely understood. Its high prevalence and the considerable effects on quality of life make IBS a disease with high social cost. Recent studies suggest that low grade mucosal immune activation, increased intestinal permeability and the altered host-microbiota interactions that modulate innate immune response, contribute to the pathophysiology of IBS. However, the understanding of the precise molecular pathophysiology remains largely unknown.

Methodology and Findings

In this study our objective was to evaluate the TLR expression as a key player in the innate immune response, in the colonic mucosa of IBS patients classified into the three main subtypes (with constipation, with diarrhea or mixed). TLR2 and TLR4 mRNA expression was assessed by real time RT-PCR while TLRs protein expression in intestinal epithelial cells was specifically assessed by flow cytometry and immunofluorescence. Mucosal inflammatory cytokine production was investigated by the multiplex technology. Here we report that the IBS-Mixed subgroup displayed a significant up-regulation of TLR2 and TLR4 in the colonic mucosa. Furthermore, these expressions were localized in the epithelial cells, opening new perspectives for a potential role of epithelial cells in host-immune interactions in IBS. In addition, the increased TLR expression in IBS-M patients elicited intracellular signaling pathways resulting in increased expression of the mucosal proinflammatory cytokines IL-8 and IL1β.

Conclusions

Our results provide the first evidence of differential expression of TLR in IBS patients according to the disease subtype. These results offer further support that microflora plays a central role in the complex pathophysiology of IBS providing novel pharmacological targets for this chronic gastrointestinal disorder according to bowel habits.

An update of the role of nutritional therapy in the management of Crohn's disease

Crohn's disease is an increasingly global health concern. Currently without a cure, it significantly alters the quality of life of Crohn's disease sufferers and places a heavy financial burden on the community. Recent reports show that the rising prevalence of Crohn's disease is no longer confined to Western countries, with considerable increases seen particularly in Asia. Nutritional problems are often associated with Crohn's disease, most notably in the paediatric population, with underweight and stunting commonly seen at presentation. In addition, linear growth retardation and pubertal delay can also manifest in these younger patients. Therefore, exclusive enteral nutrition has been used as a therapeutic option to treat Crohn's disease, in part to address the nutritional complications of the disease. Exclusive enteral nutrition can improve nutrition as well as induce remission at a rate equivalent to corticosteroids. It is safe particularly with long-term use and can induce mucosal healing, considered the gold standard for therapy, at a rate superior to corticosteroids. Exclusive enteral nutrition has thus become the preferred therapeutic option in many centres for the treatment of paediatric Crohn's disease. This review discusses the role of exclusive enteral nutrition as a therapeutic option for the treatment of Crohn's disease, as well as the latest findings into its mechanisms of action.

A meta-analysis of the effect of combinations of immune modulating nutrients on outcome in patients undergoing major open gastrointestinal surgery

BACKGROUND

Immune modulating nutrition (IMN) has been shown to reduce complications after major surgery, but strong evidence to recommend its routine use is still lacking.

OBJECTIVE

The aim of this meta-analysis was to evaluate the impact of IMN combinations on postoperative infectious and noninfectious complications, length of hospital stay, and mortality in patients undergoing major open gastrointestinal surgery.

METHODS

Randomized controlled trials published between January 1980 and February 2011 comparing isocaloric and isonitrogenous enteral IMN combinations with standard diet in patients undergoing major open gastrointestinal surgery were included. The quality of evidence and strength of recommendation for each postoperative outcome were assessed using the GRADE approach and the outcome measures were analyzed with RevMan 5.1 software (Cochrane Collaboration, Copenhagen, Denmark).

RESULTS

Twenty-six randomized controlled trials enrolling 2496 patients (1252 IMN and 1244 control) were included. The meta-analysis suggests strong evidence in support of decrease in the incidence of postoperative infectious [risk ratio (RR) (95% confidence interval [CI]): 0.64 (0.55, 0.74)] and length of hospital stay [mean difference (95% CI): -1.88 (-2.91, -0.84 days)] in those receiving IMN. Even though significant benefit was observed for noninfectious complications [RR (95% CI): 0.82 (0.71, 0.95)], the quality of evidence was low. There was no statistically significant benefit on mortality [RR (95% CI): 0.83 (0.49, 1.41)].

CONCLUSIONS

IMN is beneficial in reducing postoperative infectious and noninfectious complications and shortening hospital stay in patients undergoing major open gastrointestinal surgery.