Low Tryptophan Concentrations Research Articles

Laboratory parameters related to disease severity and physical performance after reconvalescence of acute COVID-19 infection

Research into the molecular basis of disease trajectory and Long-COVID is important to get insights toward underlying pathophysiological processes. The objective of this study was to investigate inflammation-mediated changes of metabolism in patients with acute COVID-19 infection and throughout a one-year follow up period. The study enrolled 34 patients with moderate to severe COVID-19 infection admitted to the University Clinic of Innsbruck in early 2020. The dynamics of multiple laboratory parameters (including inflammatory markers [C-reactive protein (CRP), interleukin-6 (IL-6), neopterin] as well as amino acids [tryptophan (Trp), phenylalanine (Phe) and tyrosine (Tyr)], and parameters of iron and vitamin B metabolism) was related to disease severity and patients’ physical performance. Also, symptom load during acute illness and at approximately 60 days (FU1), and one year after symptom onset (FU2) were monitored and related with changes of the investigated laboratory parameters: During acute infection many investigated laboratory parameters were elevated (e.g., inflammatory markers, ferritin, kynurenine, phenylalanine) and enhanced tryptophan catabolism and phenylalanine accumulation were found. At FU2 nearly all laboratory markers had declined back to reference ranges. However, kynurenine/tryptophan ratio (Kyn/Trp) and the phenylalanine/tyrosine ratio (Phe/Tyr) were still exceeding the 95th percentile of healthy controls in about two thirds of our cohort at FU2. Lower tryptophan concentrations were associated with B vitamin availability (during acute infection and at FU1), patients with lower vitamin B12 levels at FU1 had a prolonged and more severe impairment of their physical functioning ability. Patients who had fully recovered (ECOG 0) presented with higher concentrations of iron parameters (ferritin, hepcidin, transferrin) and amino acids (phenylalanine, tyrosine) at FU2 compared to patients with restricted ability to work. Persistent symptoms at FU2 were tendentially associated with IFN-γ related parameters. Women were affected by long-term symptoms more frequently. Conclusively, inflammation-mediated biochemical changes appear to be related to symptoms of patients with acute and Long Covid.

Serum amino acid profiles in clinically normal Noma horses.

Plasma or serum amino acids are used to evaluate nutritional status and metabolic disorders. In this study, we aimed to set reference values of serum amino acid concentrations in the Noma horse, a Japanese native horse. Thirty-one horses were classified into six age groups: neonatal foal (0-4 days), foal (0.5-1 years), youth (5 years), middle age (10 years), old (15 years), and extra-old (>20 years). Horses >5 years of age were analyzed together as the adult group. In the adult horses, there were no significant differences among the serum amino acid concentrations of each age group. The foal group had higher concentrations of alanine, aspartic acid, glutamic acid, α-aminoadipic acid, and 3-methyl-histidine than the adult group. The neonatal foal group had higher serum concentrations of phenylalanine, lysine, alanine, proline, aspartic acid, glutamic acid, β-alanine, and β-amino-iso-butyric acid and lower tryptophan concentrations and Fischer's ratios than the adult group. The neonatal foal group had higher β-amino-iso-butyric acid concentrations and lower tryptophan and 3-methyl-histidine concentrations than the foal group. Therefore, reference values might be set separately in neonatal foals, foals, and adult horses. The data for the serum amino acid concentrations can be used for health care through physiological and pathological evaluations in Noma horses.

227-LB: Kynurenine Pathway Is Associated with Preservation of Beta-Cell Function in Autoimmune Diabetes

Background: Autoimmune diabetes (AD) results from a loss of immune tolerance leading to the destruction of β-cells in the pancreas. Heterogeneity in severity of β-cell damage among people with AD is well-recognized, with some patients retaining a certain amount of insulin-producing cells for years despite the presence of pancreatic autoimmunity. Cellular and molecular mechanisms driving the preservation of β-cell function in AD remain unclear. Aim & Methods: To identify metabolic pathways associated with preservation of β-cell function we conducted a metabolomic study using gas and liquid chromatography-mass spectrometry (GC- and LC-MS) based platform on plasma samples collected from 32 subjects with adult-onset AD (median [Q1-Q3] age: 57 [52-62]; disease duration: 4.5 [3.0-9.0] years) with different severity of β-cell dysfunction, compared with data from people with rheumatoid arthritis (RA, n=28). Metabolome profiles of pancreatic islets from healthy donors after in vitro treatment with proinflammatory cytokines was also evaluated. Results: Metabolomic analyses showed decreased plasma Kynurenine/Tryptophan ratio (KynTr), a marker of indoleamine 2,3 dioxygenase-1 (IDO1) activity, in people with AD compared to RA (0.023 vs 0.027, p=0.03). Among people with AD, KynTr was directly associated with fasting C-peptide levels (rho=0.365), independently of age, gender, body mass index, diabetes duration and Hba1c (p-value after adjustments= 0.003). Lower concentrations of Tryptophan was observed in pancreatic islets from healthy donors after treatment with proinflammatory cytokines. Conclusions: While confirming that IDO1 impairment is involved in the pathogenesis of AD and in the regulation of inflammatory response of pancreatic islets, our results show that KynTr is a marker of beta-cell damage in AD. Overall, this suggests that the kynurenine pathway may be studied as a possible target for therapies aimed at preserving beta-cell function also after a diagnosis of AD Disclosure E. Maddaloni: Consultant; Abbott, Merck KGaA, PIKDARE S. p. A., Speaker's Bureau; Medical Technology & Devices. F. Dotta: None. P. Marchetti: None. R. Buzzetti: None. A. Gastaldelli: Advisory Panel; Pfizer Inc., Novo Nordisk, Merck Sharp & Dohme Corp., Boehringer Ingelheim International GmbH, Consultant; Boehringer Ingelheim International GmbH, Eli Lilly and Company, Fractyl Health, Inc., Merck Sharp & Dohme Corp., Other Relationship; Pfizer Inc., Speaker's Bureau; Eli Lilly and Company. L. Navarini: Consultant; AbbVie Inc., Pfizer Inc., Bristol Myers, Celgene, MSD Life Science Foundation, Eli Lilly and Company, Novartis, Janssen Global Services, LLC. R. Amendolara: None. S. Fenizia: None. S. Pezzica: None. M. Tesi: None. L. D'onofrio: None. E. Bosi: None. Funding Italian Ministry of University and Research (PRIN 2017: 20175L9H7H)

Thermodynamics, Kinetics, Morphology, and Raman studies for sH Hydrate of Methane and Cyclooctane

Natural gas is expected to be the major energy source in the near future, and storing it in the form of gas hydrate is a safe, clean, and economical approach. However, required thermodynamic conditions and slow kinetics are the key challenges that need to address for process viability. This study involves an experimental investigation of methane and cyclooctane sH hydrate formation for possible applications in gas storage using thermodynamics, kinetics, morphology, and Raman analysis. The hydrate formation is carried out at such thermodynamic conditions where only sH hydrate would form. The four-phase (Lw-LHC-H-V) sH hydrate equilibrium is studied for the methane and cyclooctane system via dissociation along the phase boundary method which is a robust method as it delivers a greater number of equilibrium data points in a single experimental run compared to other available methods. The sH hydrate formation helps in lowering the equilibrium conditions compared with sI hydrate formation. The slow sH hydrate formation kinetics can be improved by using low tryptophan concentrations. In this work, 0.1 wt % is the optimum tryptophan concentration as the gas uptake, and the hydrate formation rate is found to be the highest compared to 0.01, 0.05, and 1 wt % tryptophan concentrations. Here, we also visually investigate the sH hydrate formation and observed that the hydrate formation occurs below the interface for the system with no tryptophan; however, hydrate formation occurrence above the interface increases with an increase in the tryptophan concentration. The increase in the hydrate formation could be dedicated to the increased gas uptake due to the increasingly porous nature of hydrate formation. The Raman analysis confirmed the presence of methane and cyclooctane in sH hydrate cages. The higher intensity of the peaks using tryptophan additionally confirms the higher hydrate formation compared to the system with no tryptophan.

METABOLOMIC SIGNATURES OF BRAIN ATROPHY PATTERNS IN AGING AND ALZHEIMER'S DISEASE

Abstract Can plasma metabolomics reveal mechanisms of brain aging? We investigated metabolomic signatures of brain atrophy patterns related to cognitive decline and Alzheimer’s disease(AD) risk. Relationships between metabolomics(Biocrates-p500) and annual rates of change in two neuroimaging-based brain atrophy patterns(SPARE-BA indexing brain aging, SPARE-AD indexing AD-related atrophy) were examined using multivariable linear regression in 477 Baltimore Longitudinal Study of Aging participants aged 60+, adjusted for demographic variables and BMI. Higher concentrations of sarcosine, triglycerides, diglycerides, and ceramides and lower concentrations from phosphatidylcholines and cholesteryl ester were associated with faster rates of SPARE-BA increase longitudinally. Higher concentrations of diglyceride and alpha-amino-butyric acid and lower concentrations of tryptophan, hippuric acid, cholesteryl ester, phosphatidylcholine and sphingomyelin were associated with faster rates of SPARE-AD. Metabolites have differential associations with age-related and AD-related brain atrophy patterns, which may provide new insights into preventive and therapeutic interventions. Future studies should examine whether metabolite changes precede brain atrophy patterns.

Effect of 5-Hydroxytryptophan on Fatigue in Quiescent Inflammatory Bowel Disease: A Randomized Controlled Trial

Fatigue is highly prevalent among patients with inflammatory bowel disease (IBD), and only limited treatment options are available. Based on the hypothetical link between low serum tryptophan concentrations and fatigue, we determined the effect of 5-hydroxytryptophan supplementation on fatigue in patients with inactive IBD. A multicenter randomized controlled trial was performed at 13 Belgian hospitals, including 166 patients with IBD in remission but experiencing fatigue, defined by a fatigue visual analog scale (fVAS) score of ≥5. Patients were treated in a crossover manner with 100 mg oral 5-hydroxytryptophan or placebo twice daily for 2 consecutive periods of 8 weeks. The primary end point was the proportion of patients reaching a ≥20% reduction in fVAS after 8 weeks of intervention. Secondary outcomes included changes in serum tryptophan metabolites, Functional Assessment of Chronic Illness Therapy Fatigue scale, and scores for depression, anxiety, and stress. The effect of the intervention on the outcomes was evaluated by linear mixed modeling. During 5-hydroxytryptophan treatment, a significant increase in serum 5-hydroxytryptophan (estimated mean difference, 52.66 ng/mL; 95% confidence interval [CI], 39.34-65.98 ng/mL; P < .001) and serotonin (3.0 ng/mL; 95 CI, 1.97-4.03 ng/mL; P < .001) levels was observed compared with placebo. The proportion of patients reaching ≥20% reduction in fVAS was similar in placebo- (37.6%) and 5-hydroxytryptophan (35.6%)-treated patients (P= .830). The fVAS reduction (-0.18; 95% CI,-0.81 to 0.46; P= .581) and Functional Assessment of Chronic Illness Therapy Fatigue scale increase (0.68; 95% CI,-2.37 to 3.73; P= .660) were both comparable between 5-hydroxytryptophan and placebo treatment as well as changes in depression, anxiety, and stress scores. Despite a significant increase in serum 5-hydroxytryptophan and serotonin levels, oral 5-hydroxytryptophan did not modulate IBD-related fatigue better than placebo. (Trial Registration: Belgian Federal Agency for Medication and Health Products, EudraCT number: 2017-005059-10 and ClinicalTrials.gov: NCT03574948, https://clinicaltrials.gov/ct2/show/NCT03574948.).

Nutrient content and in vitro degradability of the palm kernel meal produced in the state of Chiapas, Mexico, as feed for ruminants

Objective: The objective of this study was to determine the nutritional content of palm kernel meal (PM) produced in the state of Chiapas, Mexico, as feed for ruminants. Design/Methodology/Approach: The following were determined: content of dry matter (DM), total protein (TP), ethereal extract (EE), ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), amino acids, long chain fatty acids (LCFA), minerals, polyphenols, and the in vitro degradability of DM (IDDM), of the NDF (IDNDF), and of the ADF (IDADF). Results: The contents were: DM 92.23%, TP 10.56%, EE 7.2%, ash 3,09%, NDF 76,56% and ADF 57,20%. The PM had low concentration of lysine (0.3%), methionine (0.228%) and tryptophan (0.095%), and high contents of lauric acid (50.49%), palmitic acid (10.92%), stearic acid (19.725%), oleic acid (13.56%), copper (23.3 mg kg-1), iron (230.5 mg kg-1), zinc (78.47 mg kg-1) and total phenols (7.8 mg g-1), although the IDDM (46.02%), IDNDF (29.91%) and IDADF (27.61%) were low. Findings/Conclusions: The PM, as byproduct of the oil agroindustry, has some important nutritional characteristics to be used as feed for ruminants. It is recommended to conduct a chemical analysis of this byproduct before including it in balanced meals to have an adequate balance of nutrients

Phenylketonuria oxidative stress and energy dysregulation: Emerging pathophysiological elements provide interventional opportunity.

Phenylalanine hydroxylase (PAH) deficient phenylketonuria (PKU) is rightfully considered the paradigm treatable metabolic disease. Dietary substrate restriction (i.e. phenylalanine (Phe) restriction) was applied >60 years ago and remains the primary PKU management means. The traditional model of PKU neuropathophysiology dictates blood Phe over-representation directs asymmetric blood:brain barrier amino acid transport through the LAT1 transporter with subsequent increased cerebral Phe concentration and low concentrations of tyrosine (Tyr), tryptophan (Trp), leucine (Leu), valine (Val), and isoleucine (Ile). Low Tyr and Trp concentrations generate secondary serotonergic and dopaminergic neurotransmitter paucities, widely attributed as drivers of PKU neurologic phenotypes. White matter disease, a central PKU characteristic, is ascribed to Phe-mediated tissue toxicity. Impaired cerebral protein synthesis, by reduced concentrations of non-Phe large neutral amino acids, is another cited pathological mechanism. The PKU amino acid transport model suggests Phe management should be more efficacious than is realized, as even early identified, continuously treated patients that retain therapy compliance into adulthood, demonstrate neurologic disease elements. Reduced cerebral metabolism was an early-recognized element of PKU pathology. Legacy data (late 1960's to mid-1970's) determined the Phe catabolite phenylpyruvate inhibits mitochondrial pyruvate transport. Respirometry of Pahenu2 cerebral mitochondria have attenuated respiratory chain complex 1 induction in response to pyruvate substrate, indicating reduced energy metabolism. Oxidative stress is intrinsic to PKU and Pahenu2 brain tissue presents increased reactive oxygen species. Phenylpyruvate inhibits glucose-6-phosphate dehydrogenase that generates reduced niacinamide adenine dinucleotide phosphate the obligatory cofactor of glutathione reductase. Pahenu2 brain tissue metabolomics identified increased oxidized glutathione and glutathione disulfide. Over-represented glutathione disulfide argues for reduced glutathione reductase activity secondary to reduced NADPH. Herein, we review evidence of energy and oxidative stress involvement in PKU pathology. Data suggests energy deficit and oxidative stress are features of PKU pathophysiology, providing intervention-amenable therapeutic targets to ameliorate disease elements refractory to standard of care.

Substrate-induced differential degradation and partitioning of the two tryptophan permeases Tat1 and Tat2 into eisosomes in Saccharomyces cerevisiae.

Tryptophan is a relatively rare amino acid whose influx is strictly controlled to meet cellular demands. The yeast Saccharomyces cerevisiae has two tryptophan permeases, namely Tat1 (low-affinity type) and Tat2 (high-affinity type). These permeases are differentially regulated through ubiquitination based on inducible conditions and dependence on arrestin-related trafficking adaptors, although the physiological significance of their degradation remain unclear. Here, we demonstrated that Tat2 was rapidly degraded in an Rsp5-Bul1-dependent manner upon the addition of tryptophan, phenylalanine, or tyrosine, whereas Tat1 was unaffected. The expression of the ubiquitination-deficient variant Tat25K>R led to a reduction in cell yield at 4μg/mL tryptophan, suggesting the occurrence of an uncontrolled, excessive consumption of tryptophan at low tryptophan concentrations. Eisosomes are membrane furrows that are thought to be storage compartments for some nutrient permeases. Tryptophan addition caused rapid Tat2 dissociation from eisosomes, whereas Tat1 distribution was unaffected. The 5K>R mutation had no marked effect on Tat2 dissociation, suggesting that dissociation is independent of ubiquitination. Interestingly, the D74R mutation, which was created within the N-terminal acidic patch, stabilized Tat2 while reducing the degree of partitioning into eisosomes. Moreover, the hyperactive I285V mutation in Tat2, which increases Vmax/Km for tryptophan import by 2-fold, reduced the degree of segregation into eisosomes. Our findings illustrate the coordinated activity of Tat1 and Tat2 in the regulation of tryptophan transport at various tryptophan concentrations and suggest the positive role of substrates in inducing a conformational transition in Tat2, resulting in its dissociation from eisosomes and subsequent ubiquitination-dependent degradation.

Association between the indole pathway of tryptophan metabolism and subclinical depressive symptoms in obesity: a preliminary study.

Converging data support the role of chronic low-grade inflammation in depressive symptomatology in obesity. One mechanism likely to be involved relies on the effects of inflammation on tryptophan (TRP) metabolism. While recent data document alterations in the indole pathway of TRP metabolism in obesity, the relevance of this mechanism to obesity-related depressive symptoms has not been investigated. The aim of this preliminary study was to assess the association between plasma levels of TRP and indole metabolites and depressive symptoms in 44 subjects with severe or morbid obesity, free of clinically relevant neuropsychiatric disorders. The interaction effect of inflammation, reflected in serum high-sensitive C-reactive protein (hsCRP) levels, and indoles on depressive symptoms was also determined. Higher serum levels of hsCRP and lower concentrations of TRP and indoles, particularly indole-3-carboxaldehyde (IAld), correlated with more severe depressive symptoms. Interestingly, the effect of high hsCRP levels in predicting greater depressive symptoms was potentiated by low IAld levels. These results comfort the link between inflammation, the indole pathway of TRP metabolism, and obesity-related depressive symptoms.

Identifying a biological signature of prenatal maternal stress.

Psychological stress affects maternal gastrointestinal (GI) permeability, leading to low-grade inflammation, which can negatively affect fetal development. We investigated a panel of circulating markers as a biological signature of this stress exposure in pregnant women with and without the stress-related GI disorder irritable bowel syndrome (IBS). Markers of GI permeability and inflammation were measured in plasma from healthy and IBS cohorts of women at 15 and 20 weeks’ gestation. Biomarkers were evaluated with respect to their degree of association to levels of stress, anxiety, and depression as indicated by responses from the Perceived Stress Scale, State-Trait Anxiety Inventory, and Edinburgh Postnatal Depression Scale. High levels of stress were associated with elevations of soluble CD14, lipopolysaccharide binding protein (LBP), and tumor necrosis factor–α, while anxiety was associated with elevated concentrations of C-reactive protein (CRP) in otherwise healthy pregnancies. Prenatal depression was associated with higher levels of soluble CD14, LBP, and CRP in the healthy cohort. High levels of prenatal anxiety and depression were also associated with lower concentrations of tryptophan and kynurenine, respectively, in the IBS cohort. These markers may represent a core maternal biological signature of active prenatal stress, which can be used to inform intervention strategies via stress reduction techniques or other lifestyle approaches. Such interventions may need to be tailored to reflect underlying GI conditions, such as IBS.

Induction of Auxins Synthesis by Rhodococcus erythropolis IMV Ac-5017 with the Addition of Tryptophan to the Cultivation Medium

The ability of surfactant producers to synthesize phytohormones expands the scope of their practical application and provides prospects for the development of microbial preparations with growth-stimulating properties. The possibility to intensify the phytohormone-stimulants synthesis by bacterial strains increases the efficiency of such preparations. Aim. The aim is to research the possibility of extracellular auxin synthesis induction in the presence of tryptophan in the cultivation medium of surfactant producer Rhodococcus erythropolis IMV Ac-5017 and establish the optimal concentration of tryptophan and time of introduction into the medium to ensure maximum synthesis of auxins. Methods. Biochemical, microbiological, biotechnological. Cultivation was performed in the liquid mineral medium using ethanol and waste sunflower oil as substrates. Tryptophan was added to the medium as a 1% solution in an amount of 200 or 300 mg/l at the beginning of the cultivation process or at the end of the exponential growth phase. Phytohormones were isolated by triple extraction with organic solvents from the culture broth supernatant after surfactant extraction. Preliminary purification and concentration of phytohormones was performed by thin layer chromatography. Qualitative and quantitative determination of auxins was performed using high performance liquid chromatography. Results. It was found that regardless of the concentration and time of tryptophan introduction to the culture medium of R. erythropolis IMV Ac-5017 with both substrates, a significant increase (by two to three orders of magnitude) was observed in the amount of synthesized auxins compared to tryptophan-free medium. The highest concentration of auxins (5552–5634 μg/l) was achieved by adding 300 mg/l of tryptophan into the culture medium of R. erythropolis IMV Ac-5017 with ethanol, while without the precursor their amount was only 143 μg/l. In contrast to the cultivation of the strain on culture medium with ethanol, where the synthesis of auxins did not depend on the time of tryptophan introduction, R. erythropolis IMV Ac-5017 formed the maximum amount of auxins when 300 mg/l tryptophan was added to the culture medium with waste oil at the end of the exponential growth phase (2398 μg/l compared to 9.8 μg/l on the medium without tryptophan). As auxin compounds were identified: indole-3-acetic acid, indole-3-carboxylic acid and indole-3-butyric acid. However, the highest amount of indole-3-acetic acid was synthesized, the precursor of which is tryptophan. The synthesis of this auxin (the most common plant auxin) in the presence of 300 mg/l of tryptophan increased more than 40 times on ethanol medium and more than 700 times on medium with waste oil. Induction of auxin synthesis by strain R. erythropolis IMV Ac-5017 correlated with the activity of tryptophan transaminase: when cultured on ethanol without tryptophan, it was 138 nmol·min-1·mg-1 of protein, while cultured in the presence of precursor it was increased by 5.2 times (up to 714 nmol·min-1·mg-1 of protein). The obtained results suggest that indole-3-acetic acid biosynthesis by the strain IMV Ac-5017 occurs due to the formation of indole-3-pyruvate. Conclusions. Thus, it was established the possibility of increasing by two or three orders the amount of synthesized auxins in the case of low concentrations of tryptophan introducing to the culture medium of R. erythropolis IMV Ac-5017 not only with ethanol but also with industrial waste (waste oil). The obtained results can be considered as promising for use of exometabolites of R. erythropolis IMV Ac-5017 with growth-stimulating properties in crop production.

Immune Activation and Anemia Are Associated with Decreased Quality of Life in Patients with Solid Tumors.

Anemia often coincides with depression and impaired quality of life (QoL) in cancer patients. Sustained immune activation can lead to the development of anemia. Furthermore, it also may go along with changes in tryptophan and phenylalanine metabolism. The aim of our pilot study was to study the relationship between anemia, immune-mediated changes in amino acid metabolism, and the QoL and mood of cancer patients. Questionnaires to measure QoL and depression were completed by 152 patients with solid tumors. Hemoglobin, parameters of immune activation as well as tryptophan and phenylalanine metabolism were determined in the patients’ sera. Anemic patients (51.7%) presented with higher inflammatory markers, and a higher tryptophan breakdown with lower tryptophan concentrations. They reported an impaired QoL and had higher depression scores. Patients with an impaired QoL (65.8%) also suffered from more fatigue and impaired physical, emotional, and social functioning. They, furthermore, presented with higher concentrations of inflammatory markers (C-reactive protein (CRP) and neopterin) as well as higher tryptophan degradation (in men) and higher phenylalanine concentrations (in women). Sixty-one patients (40.1%) had (mostly mild) depression. In these patients, a higher degree of Th1 immune activation was found. The results of our study suggest that cancer-related anemia goes along with an impaired QoL, which is also associated with immune-mediated disturbances of tryptophan and phenylalanine metabolism.

The study on the effect of depression on breast cancer incidence through IDO/kynurenine pathway.

e13569 Background: Psychosocial factors have been considered as the most common causes for women with breast cancer. However, it remains unclear whether mental stress can influence cancer incidence and progression. This study aims to investigate the relationship between them and the potential molecular mechanism. Methods: Depression model was established by restricting MMTV-PyMT mice in a 50ml-fixator for 4 h per day for 21 consecutive days. Behavioral tests including light-dark box test, open-field test and force swimming test were performed. Then blood, brain and mammary samples were collected at the indicated time points. ELISA was used to detect the concentration of neurotransmitters serotonin, epinephrine and norepinephrine and inflammatory factors IL-6, TNF-a and IL-1β in brain tissue and serum. Real-time quantitative qPCR and western blot were used to detect indoleamine 2, 3-dioxygenase (IDO) expression. The level of tryptophan was measured by high performance liquid chromatography(HPLC). Flow cytometry was used to evaluate the exhaustion of CD8+ T cells. Besides, the correlation between IDO expression detected by immunohistochemistry and the severity of mammary tumors was analyzed in the tumor specimens. Results: We observed that chronic stress caused depression-like behaviors, abnormal secretion of neurotransmitters serotonin, epinephrine and norepinephrine and promoted the development of breast cancer in MMTV-PyMT mice. Depression elevated the secretion of inflammatory factors IL-6, TNF-a and IL-1β in brain tissue and serum, which upregulated the expression of IDO and decreased the level of tryptophan in mice. Furthermore, T cells are sensitive to low tryptophan concentration, so elevated IDO expression suppressed and exhausted CD8+ T cells, ultimately promoting cancer incidence. Administration of xiaoyao pill (a well-known Chinese herbal formula for treating depression) or IDO inhibitor reversed the depression-like behaviors in mice and slowed the development of breast cancer. At the same time, the analysis of clinical samples showed that depression identified by Hamilton Depression Scale(HAMD) and IDO expression in mammary tumor tissues were positively correlated with the severity of mammary tumors. Conclusions: Altogether, our results suggest that depression can promote tumor immune privilege and cancer occurrence through inducing upregulated IDO expression.

Tryptophan Intake and Tryptophan Losses in Hemodialysis Patients: A Balance Study.

Tryptophan depletion is common in hemodialysis patients. The cause of this depletion remains largely unknown, but reduced nutritional tryptophan intake, losses during dialysis or an increased catabolism due to an inflammatory state are likely contributors. Currently, little is known about tryptophan homeostasis in hemodialysis patients. We assessed dietary tryptophan intake, measured plasma tryptophan during dialysis, and measured the combined urinary and dialysate excretion of tryptophan in 40 hemodialysis patients (66 ± 15 years and 68% male). Patients had low tryptophan concentrations (27 ± 9 µmol/L) before dialysis. Mean dietary tryptophan intake was 4454 ± 1149 µmol/24 h. Mean urinary tryptophan excretion was 15.0 ± 12.3 μmol/24 h, dialysate excretion was 209 ± 67 μmol/24 h and combined excretion was 219 ± 66 µmol/24 h, indicating only 5% of dietary tryptophan intake was excreted. No associations were found between plasma tryptophan concentration and tryptophan intake, plasma kynurenine/tryptophan ratio or inflammatory markers. During dialysis, mean plasma tryptophan concentration increased 16% to 31 ± 8 µmol/L. Intradialytic increase in plasma tryptophan was associated with a lower risk of mortality, independent of age, sex and dialysis vintage (HR: 0.87 [0.76–0.99]; P = 0.04). Tryptophan intake was well above the dietary recommendations and, although tryptophan was removed during dialysis, mean plasma tryptophan increased during dialysis. The cause of this phenomenon is unknown, but it appears to be protective.

Indoleamine-pyrrole 2,3-dioxygenase-1 (IDO-1) mRNA is over-expressed in the duodenal mucosa and is negatively correlated with serum tryptophan concentrations in dogs with protein-losing enteropathy.

IntroductionDogs with protein-losing enteropathy (PLE) have decreased serum tryptophan concentrations, which may contribute to disease pathogenesis. Indoleamine-pyrrole 2,3-dioxygenase-1 (IDO-1) expression is associated with low serum tryptophan concentrations and is increased in the gastrointestinal tract of humans with inflammatory bowel disease (IBD). Therefore, the objective of our study was to determine if the mRNA expression of IDO-1 is increased in the duodenal mucosa of dogs with PLE as compared to dogs with chronic enteropathy (CE) and healthy dogs, and whether this expression is correlated with changes in serum tryptophan concentration.MethodsOur study was a retrospective study using archived paraffin-embedded duodenal biopsy specimens from 8 healthy Beagle dogs from the Iowa State University Canine Service Colony and 18 and 6 client-owned dogs diagnosed with CE and PLE, respectively at the Bristol Veterinary School. A novel RNA in situ hybridization (ISH) technology, RNAscope, was used to identify IDO-1 mRNA mucosal expression in duodenal tissues. An IDO-1 specific probe was hybridized onto 10 duodenal biopsy sections from each dog whereby RNAscope signal (mRNA expression) was quantified by a single operator using light microscopy.ResultsDogs with PLE had significantly higher mRNA expression of IDO-1 in the duodenal mucosa compared to healthy dogs (mucosal percentage IDO-1 positive: P = 0.0093, (mean ± S.D) control: 19.36 ± 7.08, PLE: 34.12 ± 5.98, average fold difference: 1.76 and mucosal IDO-1 H-score: P = 0.0356, (mean ± S.D) control: 45.26 ± 19.33, PLE: 84.37 ± 19.86, average fold difference: 1.86). The duodenal mucosal mRNA expression of IDO-1 was negatively correlated with serum tryptophan concentrations in dogs with PLE (mucosal IDO-1 H-score: Spearman’s rank correlation coefficient = -0.94, P = 0.0048).ConclusionsIn conclusion, our study suggests that decreased serum tryptophan concentrations in dogs with PLE is associated with increased intestinal IDO-1 expression. Further studies are needed to determine potential inflammatory pathways responsible for increased expression of IDO-1 in the intestinal tract of dogs with PLE.

Hyperactive mutation occurs adjacent to the essential glutamate 286 for transport in the yeast tryptophan permease Tat2

In Saccharomyces cerevisiae, high-affinity tryptophan import is mediated by the plasma membrane permease Tat2. Herein, we identified hyperactive Tat2 mutations, I285V and I285T, which allowed the cells to grow at very low tryptophan concentrations (<4 μg/mL). The Km value of wild-type Tat2 for tryptophan appeared to be 24 μg/mL, whereas that of Tat2I285V and Tat2I285T was 17 and 11 μg/mL, respectively. Normalized values of Vmax/Km for Tat2I285V- and Tat2I285T-mediated tryptophan import were 2-fold higher than that for Tat2, suggesting that these mutations increase the affinity for tryptophan, and mediate transport at very low tryptophan concentrations. I285 resides adjacent to E286, a fully conserved residue among amino acid pemreases. According to a pKa prediction for E208 (pKa ∼8.3–11.7) of Escherichia coli AdiC antiporter, a structural homologue of Tat2, the E286 carboxyl chain of Tat2 could get loaded with a proton during tryptophan/H+ symport. Hence, I285V and I285T mutations might affect the buried residue environment of Tat2, thereby facilitating tryptophan import. Additionally, Tat2I285V and Tat2I285T levels increased rapidly, and were efficiently localized to the cell surface after transferring the cells to low tryptophan medium (0.5 μg/mL). Our findings provide a clue to gain insights into the property of high-affinity transport mechanisms, and offer a unique approach to improve the functionality of broad types of amino acid permeases.

Development of Biofortified Maize Hybrids through Marker-Assisted Stacking of β-Carotene Hydroxylase, Lycopene-ε-Cyclase and Opaque2 Genes.

Traditional yellow maize though contains high kernel carotenoids, the concentration of provitamin A (proA) is quite low (<2 μg/g), compared to recommended level (15 μg/g). It also possesses poor endosperm protein quality due to low concentration of lysine and tryptophan. Natural variant of crtRB1 (β-carotene hydroxylase) and lcyE (lycopene-ε-cyclase) cause significant enhancement of proA concentration, while recessive allele, opaque2 (o2) enhances the level of these amino acids. Development of biofortified maize enriched in proA, lysine and tryptophan thus holds significance in alleviation of micronutrient malnutrition. In the present study, marker-assisted stacking of crtRB1, lcyE and o2 was undertaken in the genetic background of four maize hybrids (HQPM1, HQPM4, HQPM5, and HQPM7) popularly grown in India. HP704-22 and HP704-23 were used as donors, while four elite QPM parents viz., HKI161, HKI163, HKI193-1, and HKI193-2 were used as recipients. CrtRB1 showed severe segregation distortion, while lcyE segregated as per the expectation. Recovery of recurrent parent genome (RPG) among selected backcross progenies ranged from 89 to 93%. Introgressed progenies possessed high concentration of proA (7.38–13.59 μg/g), compared to 1.65–2.04 μg/g in the recurrent parents. The reconstituted hybrids showed an average of 4.5-fold increase in proA with a range of 9.25–12.88 μg/g, compared to original hybrids (2.14–2.48 μg/g). Similar plant-, ear-, and grain- characteristics of improved versions of both inbreds and hybrids were observed when evaluated with their respective original versions. Mean lysine (0.334%) and tryptophan (0.080%) of the improved hybrids were at par with the original versions (lysine: 0.340%, tryptophan: 0.083%). Improved hybrids also possessed similar grain yield potential (6,301–8,545 kg/ha) with their original versions (6,135–8,479 kg/ha) evaluated at two locations. This is the first study of staking crtRB1-, lcyE-, and o2-, favorable alleles in single genetic background. The improved inbreds can be effectively used as potential donor for independent and/or simultaneous introgression of crtRB1, lcyE, and o2 in the future breeding programme. These biofortified maize hybrids, rich in proA, lysine and tryptophan will hold great promise for nutritional security.

Revisiting the tryptophan-serotonin deficiency and the inflammatory hypotheses of major depression in a biopsychosocial approach.

BackgroundThe aim of this cross-sectional study was to identify important biopsychosocial correlates of major depression. Biological mechanisms, including the inflammatory and the tryptophan-serotonin deficiency hypotheses of major depression, were investigated alongside health-related quality of life, life satisfaction, and social support.MethodsThe concentrations of plasma tryptophan, plasma kynurenine, plasma kynurenic acid, serum quinolinic acid, and the tryptophan breakdown to kynurenine were determined alongside health-related quality of life (Medical Outcome Study Form, SF-36), life satisfaction (Life Satisfaction Questionnaire, FLZ), and social support (Social Support Survey, SSS) in 71 depressive patients at the time of their in-patient admittance and 48 healthy controls.ResultsCorresponding with the inflammatory hypothesis of major depression, our study results suggest a tryptophan breakdown to kynurenine in patients with major depression, and depressive patients had a lower concentration of neuroprotective kynurenic acid in comparison to the healthy controls (Mann–Whitney-U: 1315.0; p = 0.046). Contradicting the inflammatory theory, the concentrations of kynurenine (t: −0.945; df = 116; p = 0.347) and quinolinic acid (Mann-Whitney-U: 1376.5; p = 0.076) in depressive patients were not significantly different between depressed and healthy controls. Our findings tend to support the tryptophan-serotonin deficiency hypothesis of major depression, as the deficiency of the serotonin precursor tryptophan in depressive patients (t: −3.931; df = 116; p < 0.001) suggests dysfunction of serotonin neurotransmission. A two-step hierarchical linear regression model showed that low tryptophan concentrations, low social support (SSS), occupational requirements (FLZ), personality traits (FLZ), impaired physical role (SF-36), and impaired vitality (SF-36) predict higher Beck Depression Inventory (BDI-II) scores.DiscussionOur study results argue for the validity of a biopsychosocial model of major depression with multiple pathophysiological mechanisms involved.

In Silico Analysis of Riboflavin Carrier Proteins from Different Avian Species

A comparative in silico characterization of the Riboflavin carrier proteins (RCP) or Riboflavin binding proteins (RfBP) was carried out to analyze their physico-chemical, secondary structural and functional properties. The amino acid composition of Riboflavin binding/carrier proteins were obtained from biological databases.Molecular weights of all the proteins were around 27,000kD. pI value of Cariama cristatawas the highest when compared to all other proteins. The instability index of all the proteins was more than 40 showing that all of them are probably not stable. Amino acid composition of vitamin binding proteins obtained from biological databases. The composition of serine and glutamic acid was high while low concentrations of Tryptophan, valine and glycine residues were seen when compared to other amino acids. Dominance of α-helices and random coils was observed from the secondary structural analysis of the proteins. SOSUI server analysis has shown that all the proteins are soluble in nature.