Roles of Dietary Amino Acids and Their Metabolites in Pathogenesis of Inflammatory Bowel Disease. Mediators Inflamm. 2017;2017:6869259. [PMID: 28392631 PMCID: PMC5368367 DOI: 10.1155/2017/6869259]

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.

Improved colonic inflammation by nervonic acid via inhibition of NF-κB signaling pathway of DSS-induced colitis mice

BACKGROUND

Nervonic acid (C24:1^∆15, 24:1 ω-9, cis-tetracos-15-enoic acid; NA), a long-chain monounsaturated fatty acid, plays an essential role in prevention of metabolic diseases, and immune regulation, and has anti-inflammatory properties. As a chronic, immune-mediated inflammatory disease, ulcerative colitis (UC) can affect the large intestine. The influences of NA on UC are largely unknown.

PURPOSE

The present study aimed to decipher the anti-UC effect of NA in the mouse colitis model. Specifically, we wanted to explore whether NA can regulate the levels of inflammatory factors in RAW264.7 cells and mouse colitis model.

METHODS

To address the above issues, the RAW264.7 cell inflammation model was established by lipopolysaccharide (LPS), then the inflammatory factors tumor necrosis factor-α (TNF-α), Interleukin-6 (IL-6), Interleukin-1β (IL-1β), and Interleukin-10 (IL-10) were detected by Enzyme-linked immunosorbent assay (ELISA). The therapeutic effects of NA for UC were evaluated using C57BL/6 mice gavaged dextran sodium sulfate (DSS). Hematoxylin and eosin (H&E) staining, Myeloperoxidase (MPO) kit assay, ELISA, immunofluorescence assay, and LC-MS/MS were used to assess histological changes, MPO levels, inflammatory factors release, expression and distribution of intestinal tight junction (TJ) protein ZO-1, and metabolic pathways, respectively. The levels of proteins involved in the nuclear factor kappa-B (NF-κB) pathway in the UC were investigated by western blotting and RT-qPCR.

RESULTS

In vitro experiments verified that NA could reduce inflammatory response and inhibit the activation of key signal pathways associated with inflammation in LPS-induced RAW264.7 cells. Further, results from the mouse colitis model suggested that NA could restore intestinal barrier function and suppress NF-κB signal pathways to ameliorate DSS-induced colitis. In addition, untargeted metabolomics analysis of NA protection against UC found that NA protected mice from colitis by regulating citrate cycle, amino acid metabolism, pyrimidine and purine metabolism.

CONCLUSION

These results suggested that NA could ameliorate the secretion of inflammatory factors, suppress the NF-κB signaling pathway, and protect the integrity of colon tissue, thereby having a novel role in prevention or treatment therapy for UC. This work for the first time indicated that NA might be a potential functional food ingredient for preventing and treating inflammatory bowel disease (IBD).

Amino acids-targeted metabolomics reveals novel diagnostic biomarkers for ulcerative colitis and Crohn's disease

Inflammatory bowel disease (IBD), which mainly comprises ulcerative colitis (UC) and Crohn's disease (CD), is a common chronic intestinal inflammatory disease that affects the ileum, rectum, and colon. Currently, the diagnosis of IBD is based on clinical history, physical examination and complementary diagnostic tests. It is challenging for physicians to make a definitive diagnosis. This study aimed to analyze the variation in amino acid metabolites in IBD serum and to identify potential predictive biomarkers of IBD diagnosis and progression. Serum samples were collected from 158 UC patients, 130 CD patients and 138 healthy controls (HCs). The 37 amino acids in serum were determined by ultra-high-pressure liquid chromatography coupled to a mass spectrometer. A panel of three-amino-acid metabolites (taurine, homocitrulline and kynurenine) was identified as a specific biomarker panel of IBD. Receiver operating characteristic analysis (ROC) showed that the panel had a sensitivity of 88.4% with a specificity of 84.6% for discriminating CD patients from UC patients. The biomarkers identified are increased in CD compared to UC. Our approach demonstrated a strong relationship between serum amino acid levels and IBD. We successfully identified serum amino acid biomarkers associated with CD and UC. The biomarker panel has potential in clinical practice for IBD diagnosis and will provide new insights into IBD pathogenesis.

Microbiome and metabolome in inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic gastrointestinal disease of unknown etiology, involving complex interactions between the gut microbiome and host immune response. The microbial dysbiosis is well documented in IBD and significantly influences the host metabolic pathways. Thus, a metabolomic fingerprint resulting from the influence of gut dysbiosis in IBD could aid in assessing the disease activity. PubMed, Medline, Science Direct, and Web of Science were searched for studies exploring the association between microbiome and metabolome in IBD patients in the last 5 years. Additionally, references of cited original articles and reviews were further assessed for relevant work. We provide a literature overview of the recent metabolomic studies performed on patients with IBD. The findings report alterations in the metabolite levels of these patients. We also discuss the gut dysbiosis observed in IBD and its influence on host metabolic pathways such as lipids, amino acids, short-chain fatty acids, and others. IBD, being a chronic idiopathic disease, requires routine monitoring. The available non-invasive markers have their limitations. The metabolite changes account for both dysbiosis and its influence on the host's immune response and metabolism. A metabolome approach would thus facilitate the identification of surrogate metabolite markers reflecting the disease activity.

cRGD peptide incorporated with patchouli alcohol loaded silk fibroin nanoparticles for enhanced targeting of inflammatory sites in colitis

The combination therapy of strengthening inflammation regression and mucosal repair may overcome the "therapeutic ceiling" of ulcerative colitis (UC). However, poor targeting is an outstanding challenge in the preparation of drug delivery systems for UC treatment. Here, we developed anti-inflammatory drug (patchouli alcohol, PA)-loaded nanoparticles (NPs) derived from natural silk fibroin (SF) and subjected to surface functionalization with cyclo RGD peptide (cRGD). Self-assembled SF NPs realized sustained drug release. Meanwhile, cRGD functionalization yielded notably targeted drug delivery to inflamed colon, and thereby enhanced the anti-inflammatory and barrier repair capabilities of NPs. Moreover, cRGD-PASFNs regulated innate immune responses and exerted a potent therapeutic efficacy against acute colitis. Surprisingly, the cRGD-PASFNs also modulated the abnormal level of amino acids which are crucial to the integrity of the intestinal barrier. Additionally, oral delivery of this nanomedicine displayed an excellent safety profile in the mouse model. This study confers confidence for the further development of targeted precision therapy for UC and other inflammatory diseases.

Dual role of melatonin as an anti-colitis and anti-extra intestinal alterations against acetic acid-induced colitis model in rats

The available ulcerative colitis drugs exhibit limited outcomes and adverse side effects. Therefore, our study aimed to investigate the therapeutic efficacy of melatonin in acetic acid (AA)-induced colitis to establish a possible treatment for colitis and its impacts on vital organs. Following colitis induction (2 ml 5% AA, rectally), rats were orally received melatonin (5 mg/kg) once per day for 6 days after colitis induction. Then, histopathological examination of colon, kidney, liver, and spleen was conducted, interleukin-1 beta (IL-1β), tumor necrosis factor-alpha (TNF-α), myeloperoxidase (MPO), malondialdehyde (MDA), glutathione (GSH), and total antioxidant capacity (TAC) levels were assessed in colon tissue. Colitis induction in untreated rats caused necrotic effects in colon tissues, a significant increase in colonic IL-1β, TNF-α, MPO, and MDA levels, and a remarkable decrease in GSH and TAC levels in colon tissue in comparison to the control group. Meanwhile, melatonin treatment reversed these parameters by improving the microscopic and macroscopic colitis features and extra-intestinal (kidney, liver, and spleen) changes in all treated rats compared to the colitis control group. These results denote a reduction in colitis severity due to the anti-inflammatory and anti-oxidative effects of melatonin and its positive impact on the vital organs.

Modulating Effect of Paeonol on Piglets With Ulcerative Colitis

Piglet enteritis is a major problem that needs to be solved urgently in modern pig production. Paeonol (Pae) has been used as a novel treatment option due to its good medicinal value. This study purported to elucidate the regulatory mechanism of Pae on dextran sodium sulfate (DSS)-induced ulcerative colitis (UC) in weaned piglets. A total of 36 crossbred (Duroc × Landrace × Yorkshire) weaned piglets were stochastically split into six groups: the control group, DSS group, 0.2% Pae group, 0.4% Pae group, 0.8% Pae group, and mesalazine group. The control and DSS groups were fed with a basic diet, the three Pae and mesalazine groups were fed with 0.2, 0.4, 0.8%, and 2 g mesalazine per kilogram of basic diet throughout the study. On the 15th day of the test period, the control group was gavaged with 10 ml of normal saline, while the remaining five groups were gavaged with 10 ml 5% DSS solution for 13 days. The study lasted for 27 days. The results showed that the 0.8% Pae group significantly increased the average daily feed intake (ADFI) and Occludin mRNA expression in the colon of piglets (P < 0.05). The 0.2% Pae group markedly increased the average daily gain (ADG) and zonula occludens-1 (ZO-1) mRNA expression (P < 0.05). In the 0.2% and 0.4% Pae groups, the feed-to-gain ratio (F/G) was significantly reduced and the mRNA expression levels of Caspase-8, respectively, markedly enhanced the mRNA expression levels of transforming growth factor-β (TGF-β) and interleukins-4 (IL-4) (P < 0.05). In the 0.8% Pae group, the relative abundance of Campilobacterota was significantly reduced (P < 0.05). In the 0.4% Pae group, the relative abundance of Firmicutes was notably increased (P < 0.05). In the 0.2 and 0.8% Pae groups, the relative abundance of Prevotella was markedly increased (P < 0.05). In the 0.2% Pae group, the contents of propionic acid, butyric acid, and valerate acid were markedly higher (P < 0.05). Thus, it is speculated that Pae may regulate the balance of anti-inflammatory/pro-inflammatory factors, improve intestinal tight junction expression, reduce apoptosis, and improve intestinal microflora structure and growth performance of piglets, thereby restoring intestinal barrier function and alleviating DSS-induced UC in piglets.

Extracts of Waste from Poplar Wood Processing Alleviate Experimental Dextran Sulfate-Induced Colitis by Ameliorating Oxidative Stress, Inhibiting the Th1/Th17 Response and Inducing Apoptosis in Inflammatory Lymphocytes

As a fast-growing tree, poplar is widely planted and typically used for wood processing in China. During poplar wood processing, a large amount of poplar sawdust (PS) and poplar leaves (PL) are produced and abandoned. To make full use of poplar resources and clarify the use of poplar as a feed additive, the active ingredients in PS and PL were extracted and isolated, and the anti-inflammatory effects of the extracts on mice with dextran sulfate sodium (DSS)-induced colitis were investigated. In vitro anti-inflammatory experiments showed that the ethyl acetate extract of PS and PL (PSE and PLE, respectively) could significantly inhibit the proliferation of concanavalin A (Con A)-activated lymphocytes. Salicortin, tremulacin and salireposide were identified in both PSE and PLE. Oral administration of PSE and PLE rescued DSS-induced colonic shortening, repaired tissue damage, and decreased the disease activity index (DAI). The antioxidant capacity, including the increased activities of glutathione peroxidase (GSH-Px), total superoxide dismutase (T-SOD and catalase (CAT) and decreased activity of myeloperoxidase (MPO), in the colons of mice with colitis was enhanced through the activation of ERK after treatment with PSE and PLE. The ratio of Th1 to Th17 cells, which can lead to inflammation in the spleen, was significantly decreased by the administration of PSE and PLE, while the phosphorylation of related transcription factors (p65, STAT1, and STAT3) was inhibited. Furthermore, PSE and PLE could induce apoptosis in Con A-activated lymphocytes, which may be associated with the increase in p-TBK1, as the molecular docking results also indicated that salireposide in PSE and PLE could interact with the TBK1 protein. Overall, our study provides a promising feed additive for improving intestinal inflammation in animals and a method for the full utilization of poplar resources.

Analysis of the Anti-Inflammatory Capacity of Bone Broth in a Murine Model of Ulcerative Colitis

Background and Objectives: Nutritional deficiencies are one of the main triggers for the development of gastrointestinal diseases, such as ulcerative colitis (UC). Therefore, the objective of the present work consisted of determining the nutrients present in the bone broth (BB) and evaluating their anti-inflammatory properties in a murine model of UC, induced by intrarectal administration of 2, 4, 6-trinitrobenzene sulfonic acid (TNBS), and acetic acid (AcOH). The BB was prepared from the femur of bovine cattle and cooked in distilled water for 8 h at 100 ± 2 °C. Materials and Methods: The BB was administered ad libitum to BALB/c mice for 10 days before the induction of UC. Colon samples were collected for histological analysis and determination of cytokine expression levels by qPCR. Results: It was found that amino acids (AA) are the main nutritional contribution of BB, 54.56% of these correspond to essential AA. The prophylactic administration of BB in the murine model of UC reduced histological damage, decreased the expression of IL-1β (61.12%), IL-6 (94.70%), and TNF-α (68.88%), and increased the expression of INF-γ (177.06%), IL-4 (541.36%), and IL-10 (531.97%). Conclusions: This study shows that BB has anti-inflammatory properties, and its consumption can decrease the symptoms of UC.

The role of fecal sulfur metabolome in inflammatory bowel diseases

Sulfur metabolism and sulfur-containing metabolites play an important role in the human digestive system, and sulfur compounds and pathways are associated with inflammatory bowel diseases (IBD). In fact, cysteine metabolism results in the production of taurine and sulfate, and gut microbes catabolize them into hydrogen sulfide, a signaling molecule with various biological functions. Besides metabolites originating from sulfur metabolism, several other sulfur-containing metabolites of different classes were detected in human feces, consisting of non-volatile and volatile compounds. Sulfated steroids and bile acids such as taurine-conjugated bile acids are the major classes along with sulfur amino acids and sulfur-containing peptides. Indeed, sulfur-containing metabolites were described in stool samples from healthy subjects, patients suffering from colorectal cancer or IBD. In metabolomics-driven studies, around 50 known sulfur-containing metabolites were linked to IBD. Taurine, taurocholic acid, taurochenodeoxycholic acid, methionine, methanethiol and hydrogen sulfide were regularly reported in IBD studies, and most of them were elevated in stool samples from IBD patients. We summarized from this review that there is strong interplay between perturbed gut microbiota in IBD, and the consistently higher abundance of sulfur-containing metabolites, which potentially represent substrates for sulfidogenic bacteria such as Bilophila or Escherichia and promote their growth. These bacteria might shift their metabolism towards the degradation of taurine and cysteine and therefore to a higher hydrogen sulfide production.

Bioconversion of soy under the influence of Aspergillus oryzae strains producing hydrolytic enzymes

Introduction. The fungus Aspergillus oryzae is widely used in the production of fermented soy-based products. However, there is little data on how its genetic characteristics affect the biochemical and fractional composition of protein substances during fermentation and the quality of fermented products. This study aimed to investigate the conversion of soy meal under the influence of two A. oryzae strains with different morphological and cultural properties during the production of a fermented soy sauce. Study objects and methods. The study used two A. oryzae strains, RCAM 01133 and RCAM 01134, which were isolated from the industrial F-931 strain (Russian Collection of Industrial Microorganisms), a producer of hydrolytic enzymes. Micromycetes were cultivated by a solid-phase method on soy meal, followed by dry fermentation. The results were analyzed with regard to accumulation of amine nitrogen, bound and free amino acids, proteins and carbohydrates. Results and discussion. The cultivation of micromycetes resulted in a 35–38% increase in protein, a tenfold increase in free amino acids, and a 1.5–1.7 fold decrease in polysaccharides. The contents of essential amino acids in the fermented soy sauce were 1.7 and 1.2 times as high as in the initial medium (soy meal) and in the reference protein, respectively. Fermentation enhanced the biological value of proteins, increasing the amino acid scores of phenylalanine (7.3–7.7 times), phenylalanine (2 times), as well as valine, threonine, tryptophan, and lysine. The contents of protein and essential amino acids were slightly higher in the sauce with the RCAM 01133 strain. Conclusion. Fermenting soy materials with the RCAM 01133 strain of A. oryzae is an alternative way to produce food ingredients with good sensory properties containing carbohydrates and biologically complete protein in easily digestible forms.

Disrupted Circadian Rest-Activity Cycles in Inflammatory Bowel Disease Are Associated With Aggressive Disease Phenotype, Subclinical Inflammation, and Dysbiosis

Patients with inflammatory bowel disease (IBD)-Crohn's disease (CD), and ulcerative colitis (UC), have poor sleep quality. Sleep and multiple immunologic and gastrointestinal processes in the body are orchestrated by the circadian clock, and we recently reported that a later category or chronotype of the circadian clock was associated with worse IBD specific outcomes. The goal of this study was to determine if circadian misalignment by rest-activity cycles is associated with markers of aggressive disease, subclinical inflammation, and dysbiosis in IBD. A total of 42 patients with inactive but biopsy-proven CD or UC and 10 healthy controls participated in this prospective cohort study. Subjects were defined as having an aggressive IBD disease history (steroid dependence, use of biologic or immunomodulator, and/or surgery) or non-aggressive history. All participants did two weeks of wrist actigraphy, followed by measurement of intestinal permeability and stool microbiota. Wrist actigraphy was used to calculate circadian markers of rest-activity- interdaily stability (IS), intradaily variability (IV), and relative amplitude (RA). Aggressive IBD history was associated with decrease rest-activity stability (IS) and increased fragmentation compared to non-aggressive IBD and health controls at 0.39 ±.15 vs. 0.51 ± 0.10 vs. 0.55 ± 0.09 (P < 0.05) and 0.83 ± 0.20 vs. 0.72 ± 0.14 (P < 0.05) but not HC at 0.72 ± 0.14 (P = 0.08); respectively. There was not a significant difference in RA by IBD disease history. Increased intestinal permeability and increased TNF-α levels correlated with an increased rest activity fragmentation (IV) at R = 0.35, P < 0.05 and R = 0.37, P < 0.05, respectively; and decreased rest-activity amplitude (RA) was associated with increased stool calprotectin at R = 0.40, P < 0.05. Analysis of intestinal microbiota showed a significant decrease in commensal butyrate producing taxa and increased pro-inflammatory bacteria with disrupted rest-activity cycles. In this study, different components of circadian misalignment by rest-activity cycles were associated with a more aggressive IBD disease history, increased intestinal permeability, stool calprotectin, increased pro-inflammatory cytokines, and dysbiosis. Wrist activity allows for an easy non-invasive assessment of circadian activity which may be an important biomarker of inflammation in IB.

The Association of Plasma-Free Branched-Chain Amino Acids with Disease Related Parameters in Ulcerative Colitis

Branched-chain amino acids (BCAAs) are involved in immune system's metabolic pathways and play fundamental role in gut health. Our aim was to assess BCAA plasma levels in patients with ulcerative colitis (UC) and associations of plasma BCAAs with disease-related parameters. This was a case-control study in adult patients with UC and BMI-matched controls. A total of 150 volunteers were screened between May 2016 and June 2017; 43 patients and 34 healthy controls were enrolled. Medical and dietary history (3 × 24 h recalls, MedDiet score), anthropometric measurements, blood and fecal samples were collected. We measured BCAAs in plasma with gas chromatography-mass spectrometry. In patients, fecal calprotectin, lactoferrin, lysozyme and defensin were quantified. Dietary pattern was similar in patients and controls. Plasma-free BCAA profiles did not differ between groups. Regression analysis showed that i) valine was inversely associated with calprotectin (p = 0.007) and ii) isoleucine with age (p = 0.031), after adjusting for age, sex, PMS and smoking. Leucine was negatively associated with age (p = 0.015) after adjusting for age, sex and PMS, but this association vanished when smoking was introduced. No correlation was observed between total BCAAs with any of the parameters. Plasma-free valine is negatively associated with calprotectin in patients with UC.

Anti-Inflammatory Potential of Cow, Donkey and Goat Milk Extracellular Vesicles as Revealed by Metabolomic Profile

In recent years, extracellular vesicles (EVs), cell-derived micro and nano-sized structures enclosed in a double-layer membrane, have been in the spotlight for their high potential in diagnostic and therapeutic applications. Indeed, they act as signal mediators between cells and/or tissues through different mechanisms involving their complex cargo and exert a number of biological effects depending upon EVs subtype and cell source. Being produced by almost all cell types, they are found in every biological fluid including milk. Milk EVs (MEVs) can enter the intestinal cells by endocytosis and protect their labile cargos against harsh conditions in the intestinal tract. In this study, we performed a metabolomic analysis of MEVs, from three different species (i.e., bovine, goat and donkey) by mass spectroscopy (MS) coupled with Ultrahigh-performance liquid chromatography (UHPLC). Metabolites, both common or specific of a species, were identified and enriched metabolic pathways were investigated, with the final aim to evaluate their anti-inflammatory and immunomodulatory properties in view of prospective applications as a nutraceutical in inflammatory conditions. In particular, metabolites transported by MEVs are involved in common pathways among the three species. These metabolites, such as arginine, asparagine, glutathione and lysine, show immunomodulating effects. Moreover, MEVs in goat milk showed a greater number of enriched metabolic pathways as compared to the other kinds of milk.

Free Amino Acids in Three Pleurotus Species Cultivated on Agricultural and Agro-Industrial By-Products

Previous studies have demonstrated the feasibility of employing by-products of the olive and wine sectors for the production of Pleurotus mushrooms with enhanced functionalities. In this work we investigated the influence of endogenous and exogenous factors on free amino acids (FAAs) profile of Pleurotus ostreatus, P. eryngii and P. nebrodensis mushrooms produced on wheat straw (WS), alone or mixed with grape marc (GM), and on by-products of the olive industry (OL). Overall, 22 FAAs were determined in substrates and mushrooms, including all the essential amino acids, the neurotransmitter γ-aminobutyric acid (GABA) and ornithine. On a dry weight (dw) basis, total FAAs ranged from 17.37 mg/g in P. nebrodensis to 130.12 mg/g in P. ostreatus samples, with alanine, leucine, glutamine, valine and serine predominating. Similar distribution patterns were followed by the monosodium glutamate (MSG)-like, sweet and bitter FAAs. Significant differences in FAAs level were observed among the species examined and among the cultivation substrates used. Principal Component Analysis (PCA) performed on the entire FAAs profile of six Pleurotus strains, clearly separated P. ostreatus from P. eryngii and P. nebrodensis, in accordance to their phylogenetic affinity. This is the first report of FAAs in P. nebrodensis.

Fecal Amino Acid Profiles Exceed Accuracy of Serum Amino Acids in Diagnosing Pediatric Inflammatory Bowel Disease

In this prospective intention-to-diagnose pilot study, we aimed to assess accuracy of serum and fecal amino-acids to discriminate de novo pediatric inflammatory bowel disease (IBD) and non-IBD children. Patients with suspected IBD were allocated the IBD (n = 11) or non-IBD group (n = 8) following laboratory testing or endoscopy according to the revised Porto-criteria. Fecal calprotectin levels were obtained, an additional blood and fecal sample were collected. Fecal and serum amino-acid profiles were analyzed using high performance-liquid chromatography. Nine fecal amino-acids (alanine [area under the curve 0.94], citrulline [0.94], glutamine [0.89], leucine [0.98], lysine [0.89], phenylalanine [0.99], serine [0.91], tyrosine [0.96], and valine [0.95]) differed significantly between IBD and non-IBD. In serum, no significant differences were observed. This study underlines the potential of fecal amino-acids as novel, adjuvant noninvasive, and low-cost biomarkers in the diagnostic work-up of pediatric IBD detection.

Elemental Diet Enriched with Amino Acids Alleviates Mucosal Inflammatory Response and Prevents Colonic Epithelial Barrier Dysfunction in Mice with DSS-Induced Chronic Colitis

Background

Clinical data suggest that enteral nutrition (EN) effectively decreases disease activity and maintains remission in patients with inflammatory bowel disease (IBD). However, the modulatory effects of EN on the intestinal mucosal immune system remain unclear.

Aims

This study first aimed at comparing the therapeutic effects of three EN formulas on ameliorating dextran sulfate sodium- (DSS-) induced chronic colitis; with the most effective formula, we then examined its influence on the mucosal inflammatory response and epithelial barrier function.

Methods

The effect of EN formulas on colitis in mice was assessed by body weight, disease activity index scores, colon length, and H&E staining for pathological examination. Colonic and circulating cytokine expression levels and the frequencies of immune cells were also analyzed. Intestinal epithelial barrier function was evaluated by detecting tight junction proteins.

Results

We found that among the three EN formulas, an elemental diet (ED) containing enriched amino acids restored the colitis-related reduction in body weight better than the other two EN formulas. ED amino acids suppressed the release of colonic proinflammatory mediators and maintained the expression of tight junction proteins in these mice. ED amino acid treatment mitigated the colitis-induced increase in CD103⁺CD11b⁺ dendritic cells and CD4⁺ and CD8⁺ T cells and inhibited the predominant Th1/Th17 responses particularly in the colonic mucosal lamina propria of mice with colitis.

Conclusions

We showed that ED amino acids can be an effective immunomodulatory agent to reduce colitis-related inflammation by inhibiting proinflammatory mediators and Th1/Th17 cell responses and by repairing the disrupted epithelial barrier.

Tryptophan Metabolism, Regulatory T Cells, and Inflammatory Bowel Disease: A Mini Review

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract resulting from the homeostasis imbalance of intestinal microenvironment, immune dysfunction, environmental and genetic factors, and so on. This disease is associated with multiple immune cells including regulatory T cells (Tregs). Tregs are a subset of T cells regulating the function of various immune cells to induce immune tolerance and maintain intestinal immune homeostasis. Tregs are correlated with the initiation and progression of IBD; therefore, strategies that affect the differentiation and function of Tregs may be promising for the prevention of IBD-associated pathology. It is worth noting that tryptophan (Trp) metabolism is effective in inducing the differentiation of Tregs through microbiota-mediated degradation and kynurenine pathway (KP), which is important for maintaining the function of Tregs. Interestingly, patients with IBD show Trp metabolism disorder in the pathological process, including changes in the concentrations of Trp and its metabolites and alteration in the activities of related catalytic enzymes. Thus, manipulation of Treg differentiation through Trp metabolism may provide a potential target for prevention of IBD. The purpose of this review is to highlight the relationship between Trp metabolism and Treg differentiation and the role of this interaction in the pathogenesis of IBD.

Serum amino acid profile in 51 dogs with immunosuppressant-responsive enteropathy (IRE): a pilot study on clinical aspects and outcomes

Background

Lower levels of tryptophan (TRP) have been identified in people with inflammatory bowel disease and in dogs with protein-losing enteropathy (PLE). No data on serum amino acids (AAs) but some on plasma in canine immunosuppressant-responsive enteropathy (IRE) are available. The aim of this study is to compare serum AAs between healthy and IRE dogs, considering clinicopathological variables and follow-up.

Results

Twenty-six healthy control dogs (CD) and 51 IRE dogs were included. IRE was diagnosed after the exclusion of extra-intestinal diseases and food and antibiotic responsive enteropathies. The canine chronic enteropathy clinical activity index (CCECAI) was assessed at presentation and during the clinical follow-up. In CD and IRE dogs, 19 different serum AAs were measured. IRE dogs were classified into responders, partial responders and non-responders, based on CCECAI after 1 month, and divided into PLE and non-PLE, based on albumin level. IRE dogs showed lower L-Tyrosine (TYR), L-Phenylalanine (PHE) and TRP (p < 0.001) and higher L-Serine (SER), L-Glutamic acid (GLU), L-Arginine (p < 0.001), L-Threonine (p = 0.013), Proline (p = 0.044), L-Cysteine (p = 0.003), L-Valine (p = 0.018), L-Lysine (p = 0.01) and L-Isoleucine (p = 0.005) than CDs. PLE dogs showed lower L-Histidine (HIS) (p = 0.008), PHE (p = 0.005) and TRP (p = 0.005) than non-PLE dogs. In IRE dogs, median GLU was significantly lower in dogs with BCS 3/9 than BCS 5/9 category (p = 0.036). Total protein was positively correlated with PHE and TRP (both p = 0.031, r = 0.30) and albumin was positively correlated with HIS (p = 0.025, r = 0.31), PHE and TRP (both p = 0.001, r = 0.46). HIS (p = 0.041), PHE (p = 0.047) and TRP (p = 0.044) concentrations were significantly lower in non-responders than in responders and partial responders.

Conclusions

This study may suggest further investigation on serum, HIS, PHE, TRP and TYR as markers of intestinal disease and proposed HIS, PHE and TRP as prognostic marker for response to therapy.

Gut Microbiota in Children With Cystic Fibrosis: A Taxonomic and Functional Dysbiosis

Intestinal dysbiosis has been observed in children with cystic fibrosis (CF), yet the functional consequences are poorly understood. We investigated the functional capacity of intestinal microbiota and inflammation in children with CF. Stool samples were collected from 27 children with CF and 27 age and gender matched healthy controls (HC) (aged 0.8-18 years). Microbial communities were investigated by iTag sequencing of 16S rRNA genes and functional profiles predicted using Tax4Fun. Inflammation was measured by faecal calprotectin and M2-pyruvate kinase. Paediatric CF gastrointestinal microbiota demonstrated lower richness and diversity compared to HC. CF samples exhibited a marked taxonomic and inferred functional dysbiosis when compared to HC. In children with CF, we predicted an enrichment of genes involved in short-chain fatty acid (SCFA), antioxidant and nutrient metabolism (relevant for growth and nutrition) in CF. The notion of pro-inflammatory GI microbiota in children with CF is supported by positive correlations between intestinal inflammatory markers and both genera and functional pathways. We also observed an association between intestinal genera and both growth z-scores and FEV1%. These taxonomic and functional changes provide insights into gastrointestinal disease in children with CF and future gastrointestinal therapeutics for CF should explore the aforementioned pathways and microbial changes.

Cell membrane and bioactive factors derived from mesenchymal stromal cells: Cell-free based therapy for inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are chronic inflammatory disorders of the gastrointestinal tract associated with multifactorial conditions such as ulcerative colitis and Crohn’s disease. Although the underlying mechanisms of IBD remain unclear, growing evidence has shown that dysregulated immune system reactions in genetically susceptible individuals contribute to mucosal inflammation. However, conventional treatments have been effective in inducing remission of IBD but not in preventing the relapse of them. In this way, mesenchymal stromal cells (MSC) therapy has been recognized as a promising treatment for IBD due to their immunomodulatory properties, ability to differentiate into several tissues, and homing to inflammatory sites. Even so, literature is conflicted regarding the location and persistence of MSC in the body after transplantation. For this reason, recent studies have focused on the paracrine effect of the biofactors secreted by MSC, especially in relation to the immunomodulatory potential of soluble factors (cytokines, chemokines, and growth factors) and extracellular vehicles that are involved in cell communication and in the transfer of cellular material, such as proteins, lipids, and nucleic acids. Moreover, treatment with interferon-γ, tumor necrosis factor-α, and interleukin-1β causes MSC to express immunomodulatory molecules that mediate the suppression via cell-contact dependent mechanisms. Taken together, we present an overview of the role of bioactive factors and cell membrane proteins derived from MSC as a cell-free therapy that can improve IBD treatment.

Nutritional evaluation of mixed wheat–faba bean pasta in growing rats: impact of protein source and drying temperature on protein digestibility and retention

This study aimed to evaluate the nutritional value of pasta enriched with legume or wheat gluten proteins and dried at varying temperature. A total of four isonitrogenous experimental diets were produced using gluten powder/wheat semolina (6/94, g/g) pasta and faba bean flour/wheat semolina (35/65, g/g) pasta dried at either 55°C (GLT and FLT, respectively) or 90°C (FVHT and GVHT, respectively). Experimental diets were fed to ten 1-month-old Wistar rats (body weight=176 (sem 15) g) for 21 d. Growth and nutritional, metabolic and inflammatory markers were measured and compared with an isonitrogenous casein diet (CD). The enrichment with faba bean increased the lysine, threonine and branched amino acids by 97, 23 and 10 %, respectively. Protein utilisation also increased by 75 % (P<0·01) in FLT in comparison to GLT diet, without any effect on the corrected faecal digestibility (P>0·05). Faba bean pasta diets' corrected protein digestibility and utilisation was only 3·5 and 9 %, respectively, lower than the CD. Growth rate, blood composition and muscle weights were not generally different with faba bean pasta diets compared with CD. Corrected protein digestibility was 3 % lower in GVHT than GLT, which may be associated with greater carboxymethyllysine. This study in growing rats clearly indicates improvement in growth performance of rats fed legume-enriched pasta diet compared with rats fed gluten–wheat pasta diet, regardless of pasta drying temperature. This means faba bean flour can be used to improve the protein quality and quantity of pasta.

Antioxidative Efficacy of a Pistacia Lentiscus Supplement and Its Effect on the Plasma Amino Acid Profile in Inflammatory Bowel Disease: A Randomised, Double-Blind, Placebo-Controlled Trial

Oxidative stress is present in patients with Inflammatory Bowel Disease (IBD), and natural supplements with antioxidant properties have been investigated as a non-pharmacological approach. The objective of the present study was to assess the effects of a natural Pistacia lentiscus (PL) supplement on oxidative stress biomarkers and to characterise the plasma-free amino acid (AA) profiles of patients with active IBD (Crohn's disease (CD) N = 40, ulcerative colitis (UC) N = 20). The activity was determined according to 5 ≤ Harvey Bradshaw Index ≤ 16 or 2 ≤ Partial Mayo Score ≤ 6. This is a randomised, double-blind, placebo-controlled clinical trial. IBD patients (N = 60) were randomly allocated to PL (2.8 g/day) or to placebo for 3 months being under no treatment (N = 21) or under stable medical treatment (mesalamine N = 24, azathioprine N = 14, and corticosteroids N = 23) that was either single medication (N = 22) or combined medication (N = 17). Plasma oxidised, low-density lipoprotein (oxLDL), total serum oxidisability, and serum uric acid were evaluated at baseline and follow-up. OxLDL/LDL and oxLDL/High-Density Lipoprotein (HDL) ratios were calculated. The plasma-free AA profile was determined by applying a gas chromatography/mass spectrometry analysis. oxLDL (p = 0.031), oxLDL/HDL (p = 0.020), and oxLDL/LDL (p = 0.005) decreased significantly in the intervention group. The mean change differed significantly in CD between groups for oxLDL/LDL (p = 0.01), and, in the total sample, both oxLDL/LDL (p = 0.015) and oxLDL/HDL (p = 0.044) differed significantly. Several changes were reported in AA levels. PL ameliorated a decrease in plasma-free AAs seen in patients with UC taking placebo. In conclusion, this intervention resulted in favourable changes in oxidative stress biomarkers in active IBD.

Adiponectin administration alleviates DSS-induced colonic inflammation in Caco-2 cells and mice

BACKGROUND

Adiponectin, a protein hormone produced by adipose tissues, exhibits anti-inflammatory functions in various models. This study was investigated the effects of adiponectin on dextran sodium sulfate (DSS)-colonic injury, inflammation, apoptosis, and intestinal barrier dysfunction in Caco-2 cell and mice.

MATERIALS AND METHODS

The results showed that DSS caused inflammatory response and intestinal barrier dysfunction in vitro and in vivo. Adiponectin injection alleviated colonic injury and rectal bleeding in mice. Meanwhile, adiponectin downregulated colonic IL-1β and TNF-α expressions and regulated apoptosis relative genes to attenuate DSS-induced colonic inflammation and apoptosis. Adiponectin markedly reduced serum lipopolysaccharide concentration, a biomarker for intestinal integrity, and enhanced colonic expression of tight junctions (ZO-1 and occludin). The in vitro data further demonstrated that adiponectin alleviated DSS-induced proinflammatory cytokines production and the increased permeability in Caco-2 cells.

CONCLUSION

Adiponectin plays a beneficial role in DSS-induced inflammation via alleviating apoptosis and improving intestinal barrier integrity.

Circulating miR-125a but not miR-125b is decreased in active disease status and negatively correlates with disease severity as well as inflammatory cytokines in patients with Crohn’s disease

AIM

To determine the association of circulating miR-125a/b expression with the risk and disease severity of Crohn’s disease (CD), and with inflammatory cytokines.

METHODS

Plasma samples were collected from patients with active CD (A-CD), or CD in remission (R-CD) and from healthy controls (HCs). The levels of the inflammatory cytokines interleukin-17 (IL-17), tumour necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) were measured by enzyme-linked immunosorbent assay. The expression of miR-125a/b was assessed by quantitative polymerase chain reaction (qPCR).

RESULTS

Twenty-nine A-CD patients, 37 R-CD patients, and 37 HCs were included in the study. Plasma miR-125a expression was decreased in A-CD patients compared with that in R-CD patients (P < 0.001) and HCs (P < 0.001). miR-125a expression levels enabled the differentiation of A-CD from R-CD patients [area under curve (AUC) = 0.854] and from HCs (AUC = 0.780), whereas miR-125b expression did not. miR-125a was negatively correlated with C-reaction protein (CRP) (P = 0.017), erythrocyte sedimentation rate (ESR) (P = 0.026), Crohn’s disease activity index (CDAI) (P = 0.003), IL-17 (P = 0.015), and TNF-α (P = 0.004) in A-CD patients. Furthermore, miR-125a was negatively associated with CRP (P = 0.038) and CDAI (P = 0.021) in R-CD patients. Regarding miR-125b, no association with CRP, CDAI, IL-17, TNF-α, or IFN-γ was found in A-CD or in R-CD patients. miR-125a levels gradually increased in A-CD patients who achieved clinical remission (P = 0.009) after 3-mo treatment, whereas they remained unchanged among patients who failed to achieve remission. No changes in miR-125b expression were detected in remission or non-remission patients after treatment.

CONCLUSION

Circulating miR-125a but not miR-125b is decreased in patients with active disease status and negatively correlates with disease severity and inflammatory cytokines in patients with CD.