Tryptophan Ratio Research Articles

162 The role of functional amino acids in optimizing nutrition and health

Abstract The ability of a diet or an individual protein-containing ingredient to satisfy the indispensable amino acid (IAA) requirements of an individual is a reflection of protein quality. In human nutrition, the concept of PQ is well recognized and widely applied to facilitate guidance on the extensive range of food items we consume. In the pet food industry, the concept of PQ is gaining recognition as a way in which to identify ideal candidate ingredients for diet formulation and our laboratory has recently completed a large data base of PQ estimates of typical ingredients used in the pet food industry to compliment the emerging PQ ingredient data. Our laboratory has also used more advanced methodologies, specifically the IAAO technique, to measure the dietary Phe, Trp, Met, Thr, and Lys requirements for adult dogs of small, medium and large breed dogs. The role of AA beyond support of protein turnover (adults) or protein deposition (growth) is being explored, such as the role of certain AA in behavior, immune function and inflammation. For example, the ratio of tryptophan to the large neutral amino acids of 0.75:1.0 in contrast to 0.46:1.0 resulted in better indices of gut health and may reduce agonistic behaviors both of which are underpinned by improved serotonergic status. The role of the sulfur AA in the development of dilated cardiomyopathy further highlights the role of IAA as sources for secondary metabolites, such as taurine and glutathione in supporting animal health. Indeed, many AA are becoming referred to as functional AA and the requirement of these AA may differ in healthy and challenged animals and deserve attention in dog and cat nutrition as well. Overall, the pattern of AA that defines the requirement of healthy dogs and cats, may not be the pattern that would support the animal under challenging conditions. Research into supporting different physiological challenges and how these may affect amino acid requirements is warranted.

Platelet Ido1 expression is induced during Plasmodium yoelii infection, altering plasma tryptophan metabolites

AbstractPlatelets are immune responsive in many diseases as noted by changes in platelet messenger RNA in conditions such as sepsis, atherosclerosis, COVID-19, and many other inflammatory and infectious etiologies. The malaria causing Plasmodium parasite is a persistent public health threat and significant evidence shows that platelets participate in host responses to infection. Using a mouse model of nonlethal/uncomplicated malaria, Plasmodium yoelii XNL (PyNL)-infected but not control mouse platelets expressed Ido1, a rate limiting enzyme in tryptophan metabolism that increases kynurenine at the expense of serotonin. Interferon-γ (IFN-γ) is a potent inducer of Ido1 and mice treated with recombinant IFN-γ had increased platelet Ido1 and IDO1 activity. PyNL-infected mice treated with anti-IFN-γ antibody had similar platelet Ido1 and metabolic profiles to that of uninfected controls. PyNL-infected mice become thrombocytopenic by day 7 after infection and transfusion of platelets from IFN-γ–treated wild-type mice but not Ido1−/− mice increased the plasma kynurenine-to-tryptophan ratio, indicating that platelets are a source of postinfection IDO1 activity. We generated platelet-specific Ido1 knockout mice to assess the contribution of platelet Ido1 during PyNL infection. Platelet-specific Ido1−/− mice had increased death and evidence of lung thrombi, which were not present in infected wild-type mice. Platelet Ido1 may be a significant contributor to plasma kynurenine in IFN-γ-driven immune processes and the loss of platelets may limit total Ido1, leading to immune and vascular dysfunction.

Increased Tryptophan Catabolism Provides Predictive Value to Chronic Heart Failure Patients with Low-Grade Inflammation.

Kynurenine to tryptophan ratio (KTR), which serves as an indicator for evaluating indoleamine-2,3-dioxygenase activity and inflammation, has been reported to be linked with cardiovascular incidences. However, its correlation with cardiovascular outcomes in patients suffering from heart failure (HF) remains to be explored. The objective of this study was to investigate the prognostic value of KTR in HF. The concentration of tryptophan and kynurenine were quantified by liquid chromatography-tandem mass spectrometry, and the KTR value was calculated in a population of 3150 HF patients. The correlation between plasma KTR levels and the occurrence of adverse cardiovascular events was evaluated for its prognostic value. We also assessed the role of KTR in addition to the classic inflammatory biomarker hypersensitive C-reactive protein (hs-CRP) in different subtypes of HF. We found that increased KTR levels were associated with an elevated risk and severity of the primary endpoints in different subtypes of HF. The simultaneous evaluation of KTR and hs-CRP levels enhanced risk categorization among HF patients. Furthermore, the KTR index presented complementary prognostic value for those HF patients with low-grade inflammation (hs-CRP ≤ 6mg/L). Our results indicated plasma KTR is an independent risk factor for cardiovascular events. Plasma KTR levels in patients with HF can provide both concurrent and complementary prognostic value to hs-CRP.

The Tryptophan Index Is Associated with Risk of Ischemic Stroke: A Community-Based Nested Case-Control Study.

The relative availability of the essential amino acid tryptophan in the brain, as indicated by the tryptophan index, which is the ratio of tryptophan to its competing amino acids (CAAs) in circulation, has been related to major depression. However, it remains unknown whether tryptophan availability is involved in the pathogenesis of ischemic stroke. We aimed to investigate the relationship between the tryptophan index and the risk of ischemic stroke. We performed a nested case-control study within a community-based cohort in eastern China over the period 2013 to 2018. The analysis included 321 cases of ischemic stroke and 321 controls matched by sex and date of birth. The plasma levels of tryptophan and CAAs, including tyrosine, valine, phenylalanine, leucine, and isoleucine, were measured by ultra-high-performance liquid chromatography-tandem mass spectrometry. Conditional logistic regression analyses were employed to determine incidence rate ratios (IRRs) and their 95% confidence intervals (CIs). After adjustment for body mass index, current smoking status, educational attainment, physical activity, family history of stroke, hypertension, diabetes, hyperlipidemia, and estimated glomerular filtration rate, an elevated tryptophan index was significantly associated with a reduced risk of ischemic stroke in a dose-response manner (IRR, 0.76; 95% CI, 0.63-0.93, per standard deviation increment). The plasma tryptophan or CAAs were not separately associated with the risk of ischemic stroke. The tryptophan index was inversely associated with the risk of ischemic stroke. Our novel observations suggest that the availability of the essential amino acid tryptophan in the brain is involved in the pathogenesis of ischemic stroke.

Ganoderma lucidum Polysaccharide Supplementation Significantly Activates T-Cell-Mediated Antitumor Immunity and Enhances Anti-PD-1 Immunotherapy Efficacy in Colorectal Cancer.

Ganoderma lucidum polysaccharide (GLP) is a prebiotic with immunomodulatory effects. However, the therapeutic potential of GLP in tumor immunotherapy has not been fully explored, especially in T cell-mediated antitumor immunity. In this study, we found that GLP significantly inhibited tumor growth and activated antitumor immunity in colorectal cancer (CRC). In the spleens and tumor tissues, the proportion of cytotoxic CD8+T cells and Th1 helper cells increased, while immunosuppressive Tregs decreased. Additionally, microbiota dysbiosis was alleviated by GLP, and short-chain fatty acid production was increased. Meanwhile, GLP decreased the ratio of kynurenine and tryptophan (Kyn/Trp) in the serum, which contributed to antitumor immunity of T cells. More importantly, the combination of GLP and the immune checkpoint inhibitor anti-PD-1 monoclonal antibody further enhanced the efficacy of anti-PD-1 immunotherapy. Thus, GLP as a prebiotic has the potential to be used in tumor immunotherapy.

Derangement in Nicotinamide Adenine Dinucleotide Metabolism is Observed During Acute Kidney Injury Among Male Agricultural Workers at Risk for Mesoamerican Nephropathy

IntroductionMesoamerican Nephropathy (MeN) is a chronic kidney disease (CKD) which may be caused by recurrent acute kidney injury (AKI). We investigated urinary quinolinate to tryptophan ratio (Q/T), a validated marker of nicotinamide adenine dinucleotide (NAD+) biosynthesis elevated during ischemic and inflammatory AKI, in a sugarcane worker population with high rates of MeN in Nicaragua. MethodsAmong 693 male sugarcane workers studied, we identified 45 who developed AKI during the harvest season. We matched them 1:1 based on age and job category with two comparison groups: (1) “no kidney injury,” active sugarcane workers with serum creatinine <1.1mg/dL; and (2) “CKD,” individuals no longer working in sugarcane due to their CKD, who had additional 1:1 matching for serum creatinine. We measured urine metabolites using liquid chromatography-coupled tandem mass spectrometry, and compared Q/T and other metabolic features between the AKI and comparison groups. ResultsUrine Q/T was significantly higher in workers with AKI than in those with no kidney injury (median [IQR] 0.104 [0.074-0.167] vs 0.060 [0.045-0.091], P < 0.0001) and marginally higher than in workers with CKD (0.086 (0.063-0.142), P = 0.059). Urine levels of the NAD+ precursor nicotinamide were lower in the AKI group than in comparison groups. ConclusionWorkers at risk for MeN who develop AKI demonstrate features of impaired NAD+ biosynthesis, providing new insights into the metabolic mechanisms of injury in this population. Therapeutic use of oral nicotinamide, which may ameliorate NAD+ biosynthetic derangement and fortify against kidney injury, should be investigated to prevent AKI in this setting.

Influence of cardiorespiratory fitness on obesity-associated inflammation in women and men: The FATCOR study

Background and aimsCardiorespiratory fitness has been postulated to lower chronic inflammation in obesity. We assessed sex-specific associations of inflammation with cardiorespiratory fitness in overweight and obese persons. Methods and resultsPeak oxygen uptake (VO2max) was measured by treadmill in 566 participants (age 48 ± 9 years, 60% women) with body mass index >27.0 kg/m2 in the FAT associated CardiOvasculaR dysfunction (FATCOR) study. Fitness was identified from age- and sex specific reference levels of VO2max. The inflammatory markers C-reactive protein (CRP), serum amyloid A (SAA), kynurenine:tryptophan ratio (KTR) and pyriodoxic acid ratio (PAr) were measured by mass spectrometry. In the total study population 63% had obesity and 74% were cardiorespiratory unfit. Unfit women had the highest fat percentage and the highest serum levels of CRP and SAA (p < 0.05). In multivariable linear regression analyses in women, higher CRP (β −0.15, p = 0.001), SAA (β −0.10, p = 0.03) and PAr (β −0.09, p = 0.03) were associated with lower VO2max after adjusting for confounders. In multivariable analyses in men, higher PAr (β −0.14, p = 0.02) was associated with lower VO2max. In multivariable analyses in obese women, higher CRP and PAr remained associated with lower VO2max (p < 0.05), while in obese men there was no significant association. When normalizing VO2max for fat-free mass (VO2maxFFM) higher CRP, SAA and PAr index were associated with lower VO2maxFFM in women, while only higher PAr index was associated with lower VO2maxFFM in men. ConclusionThe association of inflammation with lower cardiorespiratory fitness was more pronounced in women than men, in particular when obesity was present. Clinical trial registrationURL: http://www.clinicaltrials.gov NCT02805478.

Staunch the Age Related Decline into Dementia, Cancer, Autoimmunity (Long Covid), Obesity, and Other Diseases with a Prebiotic, Probiotic, Postbiotic Triple Play

“All diseases originate in the gut.” Hippocrates (400 BC) A healthy gut microbiome via the gut-brain-axis elevates heart rate variability (HRV), a general measure of health and well-being. A dysbiotic gut microbiome, low in biodiversity and butyrate producers, can alter tryptophan metabolism (ATM) and increase the kynurenine to tryptophan ratio (KTR) with release of proinflammatory cytokines, predominantly TNF-α, IL-6, and IL-1β. These also characterize chronic inflammation, oxidative stress, and a multitude of diseases. Also proposed is the gut-lung dysbiosis concept and consequent degradation of ACE2 (richest in lungs and gut). Leaky gut (and lung) induced autoantibodies (AAs) related to G-protein coupled receptors (GPCRs) in combination with increased Ang II further potentiate oxidative stress. The underappreciated pathogenic role of these receptors on invading Candida hyphae is explored. The efficacy of fecal microbiome transplantation (FMT) in treating dementia, cancer, and autoimmunity supports the plausibility of success with “FMT-lite”. This triple play of prebiotic (d-mannose), probiotic (bifidobacteria and lactobacilli), and postbiotic (butyrate) might improve intestinal barrier integrity, oppose entry of GPCR antigens (epitopes), suppress the inflammatory cytokine triad, balance IFN-γ and TGF-β, suppress oxidative stress, depress KTR, elevate HRV, and extend lifespan and its quality.

Staunch the Age Related Decline into Dementia, Cancer, Autoimmunity (Long Covid), Obesity, and Other Diseases with a Prebiotic, Probiotic, Postbiotic Triple Play

“All diseases originate in the gut.” Hippocrates (400 BC) A healthy gut microbiome via the gut-brain-axis elevates heart rate variability (HRV), a general measure of health and well-being. A dysbiotic gut microbiome, low in biodiversity and butyrate producers, can alter tryptophan metabolism (ATM) and increase the kynurenine to tryptophan ratio (KTR) with release of proinflammatory cytokines, predominantly TNF-α, IL-6, and IL-1β. These also characterize chronic inflammation, oxidative stress, and a multitude of diseases. Also proposed is the gut-lung dysbiosis concept and consequent degradation of ACE2 (richest in lungs and gut). Leaky gut (and lung) induced autoantibodies (AAs) related to G-protein coupled receptors (GPCRs) in combination with increased Ang II further potentiate oxidative stress. The underappreciated pathogenic role of Candida is explored. The efficacy of fecal microbiome transplantation (FMT) in treating dementia, cancer, and autoimmunity supports the plausibility of success with “FMT-lite”. This triple play of prebiotic (d-mannose), probiotic (bifidobacteria and lactobacilli), and postbiotic (butyrate) might improve intestinal barrier integrity, oppose entry of GPCR antigens, suppress the inflammatory cytokine triad, balance IFN-γ and TGF-β, suppress oxidative stress, depress KTR, elevate HRV, and extend lifespan and its quality.

Staunch the Age Related Decline into Dementia, Cancer, Autoimmunity (Long Covid), Obesity, and Other Diseases with a Prebiotic, Probiotic, Postbiotic Triple Play

“All diseases originate in the gut.” Hippocrates (400 BC) A healthy gut microbiome via the gut-brain-axis elevates heart rate variability (HRV), a general measure of health and well-being. A dysbiotic gut microbiome, low in biodiversity and butyrate producers, can alter tryptophan metabolism (ATM) and increase the kynurenine to tryptophan ratio (KTR) with release of proinflammatory cytokines, predominantly TNF-α, IL-6, and IL-1β. These also characterize chronic inflammation, oxidative stress, and a multitude of diseases. Also proposed is the gut-lung dysbiosis concept and consequent degradation of ACE2 (richest in lungs and gut). Leaky gut (and lung) induced autoantibodies (AAs) related to G-protein coupled receptors (GPCRs) in combination with increased Ang II further potentiate oxidative stress. The underappreciated pathogenic role of Candida is explored. The efficacy of fecal microbiome transplantation (FMT) in treating dementia, cancer, and autoimmunity supports the plausibility of success with “FMT-lite”. This triple play of prebiotic (d-mannose), probiotic (bifidobacteria and lactobacilli), and postbiotic (butyrate) might improve intestinal barrier integrity, oppose entry of GPCR antigens, suppress the inflammatory cytokine triad, balance IFN-γ and TGF-β, suppress oxidative stress, depress KTR, elevate HRV, and extend lifespan and its quality.

Microbial Translocation and Gut Damage Are Associated With an Elevated Fast Score in Women Living With and Without HIV.

Steatohepatitis is common in persons living with HIV and may be associated with gut microbial translocation (MT). However, few studies have evaluated the gut-liver axis in persons living with HIV. In the Women's Interagency HIV Study, we examined the associations of HIV and circulating biomarkers linked to MT and gut damage using the FibroScan-aspartate aminotransferase (FAST) score, a noninvasive surrogate for steatohepatitis with advanced fibrosis. Among 883 women with HIV and 354 without HIV, we used multivariable regression to examine the associations of HIV and serum biomarkers linked to MT and gut damage (kynurenine and tryptophan ratio, intestinal fatty acid-binding protein, soluble CD14, and soluble CD163) with a log-transformed FAST score after adjusting for key covariates. We used a path analysis and mediation models to determine the mediating effect of each biomarker on the association of HIV with FAST. HIV infection was associated with a 49% higher FAST score. MT biomarker levels were higher in women with HIV than women without HIV (P < .001 for each). MT biomarkers mediated 13% to 32% of the association of HIV and FAST score. Biomarkers linked to MT and gut damage are associated with a higher FAST score and mediate the association of HIV with a higher FAST score. Our findings suggest that MT may be an important mechanism by which HIV increases the risk of steatohepatitis with advanced fibrosis.

Correlation between serum tryptophan metabolism and treatment efficacy of dapoxetine in patients with premature ejaculation: A pilot study.

Primary premature ejaculation (PPE) is a common male neurobiological disorder. Currently, there is consensus that the impairment in central serotonin (5-HT) neurotransmission constitutes a key pathogenic factor in PPE. Selective serotonin reuptake inhibitors (SSRIs) serve as the primary pharmacological intervention; however, a comprehensive elucidation of their mechanism of action remains incomplete. Owing to significant individual variability in efficacy, SSRIs exhibit a high discontinuation rate. Hence, there is an urgent need to address the selection of SSRIs for PPE treatment. This study aims to investigate the characteristics of tryptophan (TRP) metabolism in patients with PPE and to assess its influence on the efficacy of SSRIs. The exploratory study included a total of 16 patients with PPE and 16 control subjects who were healthy men without any sexual dysfunction. Upon enrollment in the study, all participants underwent a thorough medical history review and physical examination. Subsequently, their serum levels of TRP, its metabolites, large neutral amino acids (LNAAs), and metabolite ratios were assessed using a liquid chromatography-mass spectrometry (LC-MS) assay. After a period of 4weeks of dapoxetine treatment, all patients with PPE underwent reassessment using the Premature Ejaculation Diagnostic Tool (PEDT) score and intravaginal ejaculatory latency time (IELT) test. The ratio of serum TRP to other LNAAs (TRP/LNAAs) in patients with PPE was found to be significantly lower compared to the control group (P<0.05). Conversely, the ratio of kynurenine to TRP (KYN/TRP) was observed to be significantly higher in the PPE patients compared to the control group (P<0.05). Including the serum TRP/LNAAs ratio and KYN/TRP ratio in the prediction model yielded the highest prediction efficiency for PPE. There was a significant negative correlation between the ratio of TRP/LNAAs before the treatment and the IELT after 4weeks of the treatment. Additionally, there was a significant positive correlation observed between the ratio of TRP/LNAAs before the treatment and the PEDT score after 4weeks of the treatment. This study demonstrates that the reduction in the TRP/LNAAs ratio and the elevation of the KYN/TRP ratio are significant characteristics associated with PPE. These findings suggest that diminished tryptophan availability in the brain and the activation of the kynurenine (KYN) pathway may play a role in the pathogenesis of PPE. The TRP/LNAAs ratio has potential as a reliable indicator of central serotonin (5-HT) levels. Considering the TRP/LNAAs ratio when selecting SSRIs for the treatment of PPE may enhance the response rate of this medication.

Effect of the level of somatotropin hormone in blood serum on the meat productivity of Aberdeen angus bulls

The studies were performed on Aberdeen Angus bulls at the age of 18 months. Animals, depending on the level of somatotropin in blood serum, were divided into three groups by the percentile method: group I – up to the 25th percentile; group II – within the limits of 25-75 percentiles; group III – above the 75th percentile. The somatotropin content was determined in blood serum by enzyme-linked immunoassay using an automatic microplate analyzer Infinite F200 PRO. To study the meat qualities of steers, a control slaughter was carried out at the age of 18 months. It was found that animals with the maximum level of somatotropin in the blood serum had a higher pre-slaughter mass, hot carcass weight, chilled carcass, pulp mass and bone mass, with a minimum content of internal fat in the carcasses. The chemical composition of the average sample of meat and the longest back muscle in these animals was characterized by an increased protein content and a minimum fat concentration. The protein-qualitative indicator estimated by the ratio of tryptophan to oxyproline in the longest back muscle increased with an increase in serum somatotropin.

2958. Investigating the mechanisms of persistent inflammation and the association with non-communicable diseases (NCDs), Tuberculosis (TB) recurrence, and other infections

Abstract Background TB continues to be a major cause of morbidity and mortality worldwide. Despite successful completion of anti-tuberculosis therapy (ATT), studies indicate that TB survivors (post-TB) have a significantly higher risk of mortality compared to the general population, primarily due to increased incidence of non-communicable diseases (NCDs; cardiovascular disease, cancer, lung disease) and recurrent infections. Furthermore, a considerable proportion of TB patients exhibit persistent inflammation even after ATT. Methods We enrolled 325 individuals with microbiologically confirmed pulmonary TB, diagnosed between 2014 and 2020. Blood samples were obtained at baseline and 12- months (6-months after completing antimicrobial therapy) to evaluate persistent inflammation. Plasma C-reactive protein (CRP) was used to measure inflammation. Lipid peroxidation (LP) was measured by oxidized (HNE) LDL. Redox capacity was measured via the Trolox assay. Immune activation was measured by the Indoleamine 2,3 dioxygenases (IDO) enzyme by measuring the Kynurenine-Tryptophan ratio. Results After successful TB treatment, 62% of participants exhibited persistent elevation of CRP (P&amp;lt; 0.001) (Figure 1a). Univariate analysis of the first 186 participants revealed no association between elevated post-TB inflammation and HIV status (Fig. 1B), gender, or age. Individuals with increased CRP levels had a lower redox capacity compared to those whose CRP normalized at the end of ATT (P&amp;lt; 0.001) (Figure 2). Analysis of Oxidized LDL in successfully treated TB patients demonstrated that low antioxidant capacity also had persistent LP (Figure 2b). IDO activity was increased among TB participants with high CRP, which persisted even after successful therapy in participants with high and low CRP levels (Figure 3). Fig 1a: CRP was evaluated on TB participants and their asymptomatic, healthy household contacts. The median CRP of the healthy contacts was &amp;lt;2 mg/L, whereas the median CRP for TB participants at baseline was 21 and decreased to 8 at the end of successful therapy (EOT). Previous studies have demonstrated that CRP levels &amp;gt;3 mg/L are associated with increased CVD risk . 62% (111/186) of TB participants have CRP levels &amp;gt;3 mg//L at the end of TB therapy. Fig 1b: All TB participants living with HIV (PLWH) are started on ART, with &amp;gt;90% having a viral load &amp;lt;1000 at end of therapy (EOT). At EOT, TB participants without HIV do not have lower CRP levels compared to PLWHIV, preliminarily suggesting HIV is not driving the persistent inflammation. Fig2a: The Trolox antioxidant capacity was evaluated on TB Participants with High CRP &amp;gt;3mg/L (n:36) vs Low CRP &amp;lt;3mg/L (n:32) and Healthy Controls (n:32). Conclusion This study shows that a substantial proportion of TB participants exhibit persistent inflammation and IDO activity even after ATT. Among TB participants who do not normalize inflammation at the end of successful therapy, there is also persistent LP and decreased redox capacity. This suggests that there is a bidirectional malignant relationship between LP and redox capacity. Potentially, this suggests that mitigating lipid peroxidation may help decrease post-TB inflammation. Fig2b: Oxidized LDL was measured in TB individuals with High levels of CRP High CRP &amp;gt;3mg/L (n:16) vs Low CRP &amp;lt;3mg/L (n:16) and Healthy Controls (n:4) Fig3 Plasma Kynurenine to Tryptophan ratio was evaluated in TB individuals with persistent augmented levels of CRP (n:19) at baseline and Heathy Controls. At the end of Therapy the KYN:TRYP was evaluated in TB individuals with high (n:22) and Low CRP levels (n:17) Disclosures All Authors: No reported disclosures

A systematic review and meta-analysis of the kynurenine pathway of tryptophan metabolism in rheumatic diseases.

https://www.crd.york.ac.uk/prospero, identifier CRD CRD42023443718.

Development and Optimization of a Target Engagement Model of Brain IDO Inhibition for Alzheimer's Disease.

Indoleamine 2,3-dioxygenase (IDO1) inhibition is a promising target as an Alzheimer's disease (AD) Disease-modifying therapy capable of downregulating immunopathic neuroinflammatory processes. To aid in the development of IDO inhibitors as potential AD therapeutics, we optimized a lipopolysaccharide (LPS) based mouse model of brain IDO1 inhibition by examining the dosedependent and time-course of the brain kynurenine:tryptophan (K:T) ratio to LPS via intraperitoneal dosing. We determined the optimal LPS dose to increase IDO1 activity in the brain, and the ideal time point to quantify the brain K:T ratio after LPS administration. We then used a brain penetrant tool compound, EOS200271, to validate the model, determine the optimal dosing profile and found that a complete rescue of the K:T ratio was possible with the tool compound. This LPS-based model of IDO1 target engagement is a useful tool that can be used in the development of brain penetrant IDO1 inhibitors for AD. A limitation of the present study is the lack of quantification of potential clinically relevant biomarkers in this model, which could be addressed in future studies.

Alteration of Branched-Chain and Aromatic Amino Acid Profile as a Novel Approach in Studying Polycystic Ovary Syndrome Pathogenesis.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that affects reproductive-age women and predisposes them to the development of metabolic disturbances. Recent research has shown that several metabolic factors may play a role in PCOS pathogenesis, and it has been suggested that an alteration in the amino acid profile might be a predictive sign of metabolic disorders. Metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) are concepts that have attracted scientific attention; however, a universal definition has not been established yet for these terms. Already existing definitions of MHO involve the coexistence of obesity with the absence or minimal presence of other metabolic syndrome parameters. A group of 326 women, 209 diagnosed with PCOS and 117 healthy individuals, participated in this study. Multiple parameters were assessed, including anthropometrical, biochemical, and hormonal ones, and gas-liquid chromatography, combined with tandem mass spectrometry, was used to investigate the amino acid profile. Statistical analysis revealed noticeably higher levels of all aromatic amino acids in PCOS women compared to the control group: phenylalanine 47.37 ± 7.0 vs. 45.4 ± 6.09 nmol/mL (p = 0.01), tyrosine 61.69 ± 9.56 vs. 58.08 ± 8.89 nmol/mL (p < 0.01), and tryptophan 53.66 ± 11.42 vs. 49.81 ± 11.18 nmol/mL (p < 0.01); however, there was no significant difference in the "tryptophan ratio" between the PCOS and control group (p = 0.88). A comparison of MHO and MUO PCOS women revealed that LAP, leucine, and isoleucine concentrations were significantly higher among the MUO subgroup: respectively, 101.98 ± 34.74 vs. 55.80 ± 24.33 (p < 0.001); 153.26 ± 22.26 vs. 137.25 ± 25.76 nmol/mL (p = 0.04); and 92.92 ± 16.09 vs. 82.60 ± 18.70 nmol/mL (p = 0.02). No significant differences in BMI, fasting glucose, and HOMA-IR between MHO and MUO were found: respectively, 35.0 ± 4.8 vs. 36.1 ± 4.6 kg/m2 (p = 0.59); 88.0 ± 6.0 vs. 87.73 ± 6.28 mg/dL (p = 0.67); and 3.36 ± 1.70 vs. 4.17 ± 1.77 (p = 0.1). The identification of altered amino acid profiles in PCOS holds potential clinical implications. Amino acids may serve as biomarkers for diagnosing and monitoring the metabolic status of individuals with PCOS. The alteration of BCAAs and AAAs may be involved in PCOS pathogenesis, but the underlying mechanism should be further investigated.

Non-salt based co-amorphous formulation produced by freeze-drying

Amino acids-based co-amorphous system (CAM) has shown to be a promising approach to overcome the dissolution challenge of biopharmaceutics classification system class II drugs. To date, most CAM formulations are based on salt formation at a 1:1 M ratio and are prepared by mechanical activation. However, its use in medicinal products is still limited due to the lack of in-depth understanding of non-ionic based molecular interactions. There are also limited studies on the effect of drug-to-co-former ratio, the development of more scalable, less aggressive, manufacturing processes such as freeze drying and its dissolution benefits. This work aims to investigate the effect of the ratio of tryptophan (a model non-ionic amino acid) to indomethacin (a model drug) on a non-salt-based CAM prepared via freeze-drying with the tert-butyl alcohol-water cosolvent system. The CAM material was systemically characterized at various stages of the freeze-drying process using DSC, UV–Vis, FT-IR, NMR, TGA and XRPD. Dissolution performance and physical stability upon storage were also investigated. Freeze-drying using the cosolvent system has been successfully shown to produce CAMs. The molecular interactions involving H-bonding, H/π and π–π between compounds have been confirmed by FT-IR and NMR. The drug release rate for formulations with a 1.5:1 drug: amino acid molar ratio (or 1:0.42 wt ratio) or below is found to be significantly improved compared to the pure crystalline drug. Furthermore, formulation with a 2.3:1 drug:amino acid molar ratio (or 1:0.25 wt ratio) or below have shown to be physically stable for at least 9 months when stored at dry condition (5% relative humidity, 25 °C) compared to the pure amorphous indomethacin. We have demonstrated the potential of freeze-drying using tert-butyl alcohol-water cosolvent system to produce an optimal non-salt-based class II drug-amino acid CAM.

Evaluation of neopterin levels and kynurenine pathway in patients with acute coronary syndrome.

Coronary atherosclerosis is the leading cause of coronary artery disease. Several investigations have indicated that tear-sensitive plaques contain macrophages and T cells. Neopterin is an essential cellular immune response biomarker. The main goal of this study was to see if there were any changes in biomarkers like unconjugated pteridines, neopterin, and biopterin, as well as kynurenine pathway enzymes like indoleamine 2,3-dioxygenase (IDO), which catalyzes the rate-limiting step in tryptophan degradation, in patients with the acute coronary syndrome (ACS) caused by angiographic atherosclerosis. High-performance liquid chromatography was used to determine the amounts of neopterin, biopterin, and creatinine in urine samples, as well as tryptophan and kynurenine in serum samples. The enzyme-linked immunosorbent assay was used to assess the amounts of neopterin in serum samples. The measured parameters were evaluated between ACS patients and controls. The measured levels of neopterin, biopterin and the kynurenine to tryptophan ratio reflecting IDO activity, and the specifically known biomarkers such as cardiac troponin, creatine kinase, myoglobin, and natriuretic peptides are statistically higher in ACS patients compared to control subjects. On the other hand, the measured parameters are inadequate to classify the conventional kinds of ACS, ST-elevation- and non-ST-elevation- myocardial infarction. The study found that determining and using neopterin and IDO parameters as biomarkers in individuals with the ACS can support traditional biomarkers. However, it can be concluded that evaluating pteridine biomarkers solely have no privilege to clinical findings in ACS diagnosis and classification.

Adipocyte-derived kynurenine stimulates malignant transformation of mammary epithelial cells through the aryl hydrocarbon receptor

Anti-hormone therapies are not efficacious for reducing the incidence of triple negative breast cancer (TNBC), which lacks both estrogen and progesterone receptors. While the etiology of this aggressive breast cancer subtype is unclear, visceral obesity is a strong risk factor for both pre- and post-menopausal cases. The mechanism by which excessive deposition of visceral adipose tissue (VAT) promotes the malignant transformation of hormone receptor-negative mammary epithelial cells is currently unknown. We developed a novel in vitro system of malignant transformation in which non-tumorigenic human breast epithelial cells (MCF-10A) grow in soft agar when cultured with factors released from VAT. These cells, which acquire the capacity for 3D growth, show elevated aryl hydrocarbon receptor (AhR) protein and AhR target genes, suggesting that AhR activity may drive malignant transformation by VAT. AhR is a ligand-dependent transcription factor that generates biological responses to exogenous carcinogens and to the endogenous tryptophan pathway metabolite, kynurenine. The serum kynurenine to tryptophan ratio has been shown to be elevated in patients with obesity. Herein, we demonstrate that AhR inhibitors or knockdown of AhR in MCF-10A cells prevents VAT-induced malignant transformation. Specifically, VAT-induced transformation is inhibited by Kyn-101, an inhibitor for the endogenous ligand binding site of AhR. Mass spectrometry analysis demonstrates that adipocytes metabolize tryptophan and release kynurenine, which is taken up by MCF-10A cells and activates the AhR to induce CYP1B1 and promote malignant transformation. This novel hormone receptor-independent mechanism of malignant transformation suggests targeting AhR for TNBC prevention in the context of visceral adiposity.