Akkermansia muciniphila inhibits tryptophan metabolism via the AhR/ß-catenin signaling pathway to counter the progression of colorectal cancer.

Akkermansia muciniphila (A. muciniphila), a gram-negative anaerobic bacterium, is selectively decreased in the fecal microbiota of patients with colorectal cancer (CRC), but its molecular mechanism in CRC development remains inconclusive. In this study, we first confirmed the inhibitory effect of A. muciniphila on CRC formation and analyzed the metabolic role of intestinal flora in human Polyps, A-CRA (advanced colorectal adenoma) and CRC samples. To better clarify the role of A. muciniphila in CRC development, a pseudo-germ-free (GF) azoxymethane (AOM)/dextran sulfate sodium (DSS) mouse model was established, followed by infection with or without A. muciniphila. Metabolomic analysis and RNA-seq analysis showed tryptophan-mediated aryl hydrocarbon receptor (AhR) was significantly down-regulated in A. muciniphila-infected CRC mice. Then, mice with intestinal specific AhR deficiency (AhRfl/fl Cre) were generated and were used in 2 murine models: AOM/DSS treatment as a model of carcinogen-induced colon cancer and a genetically induced model using ApcMin/+ mice. Notably, AhR deficiency inhibited CRC growth in the AOM/DSS and ApcMin/+ mouse model. Moreover, AhR deficiency inhibited, rather than enhanced, tumor formation and tumor-derived organoids in Apc-deficient cells both in vivo and in vitro by activating Wnt/ß-catenin signaling and TCF4/LEF1-dependent transcription. Furthermore, the antitumor effectiveness of A. muciniphila was abolished either in a human colon cancer tumor model induced by subcutaneous transplantation of AhR-silenced CRC cells, or AhR-deficienty spontaneous colorectal cancer model. In conclusion, supplementation with A. muciniphila. protected mice from CRC development by specifically inhibiting tryptophan-mediated AhR/ß-catenin signaling.

Saussurea involucrata oral liquid regulates gut microbiota and serum metabolism during alleviation of collagen-induced arthritis in rats.

Saussurea involucrata oral liquid (SIOL) can clinically relieve symptoms, such as joint pain and swelling, and morning stiffness, in patients with rheumatoid arthritis (RA). However, the mechanism of action remains unclear. This study used a combination of gut microbiota and serum metabolomics analysis to investigate the effects and potential mechanisms of SIOL intervention on rats with RA induced by type II bovine collagen and Freund's complete adjuvant. Results showed that SIOL treatment consequently improved the degree of ankle joint swelling, joint histopathological changes, joint pathological score, and expression of serum-related inflammatory cytokines (interleukin (IL)-1ß, IL-4, IL-6, IL-10, and tumor necrosis factor-α) in RA model rats. 16 S rRNA sequencing results showed that SIOL increased the relative richness of the Lactobacillus and Bacteroides genus and decreased the relative richness of Romboutsia, Alloprevotella, Blautia, and Helicobacter genus. Serum nontargeted metabolomic results indicated that SIOL could regulate metabolites related to metabolic pathways, such as glycine, serine, threonine, galactose, cysteine, and methionine metabolism. Spearman correlation analysis showed that the regulatory effects of SIOL on the tricarboxylic acid (TCA) cycle, phenylalanine metabolism, phenylalanine, tyrosine, and tryptophan biosynthesis, and glyoxylate and dicarboxylate metabolism pathways were correlated with changes in the richness of the Lactobacillus, Romboutsia, Bacteroides, and Alloprevotella genus in the gut microbiome. In conclusion, this study revealed the ameliorative effects of SIOL on RA and suggested that the therapeutic effects of SIOL on RA may be related to the regulation of the community richness of the Lactobacillus, Romboutsia, Bacteroides, and Alloprevotella genus, thereby improving the TCA cycle; phenylalanine metabolism; phenylalanine, tyrosine, and tryptophan biosynthesis, and glyoxylate and dicarboxylate metabolism-related pathways.

Hypothesis: Metabolic targeting of 5-aminolevulinate synthase by tryptophan and inhibitors of heme utilisation by tryptophan 2,3-dioxygenase as potential therapies of acute hepatic porphyrias.

Metabolic targeting of liver 5-aminolevulinate synthase (5-ALAS) by inhibition of heme utilisation by tryptophan (Trp) 2,3-dioxygenase (TDO) or the use of tryptophan is proposed as a therapy of acute hepatic porphyrias. 5-ALAS, the rate-limiting enzyme of heme biosynthesis, is under negative feedback control by a small regulatory heme pool in the hepatic cytosol. Acute porphyric attacks, precipitated by fasting, certain hormones and some drugs, involve induction of 5-ALAS secondarily to depletion of the above pool, and the resultant elevation of 5-ALA levels initiates the abdominal and neurological symptoms of attacks. By utilising the regulatory heme, cytosolic TDO undermines the feedback control, thus allowing 5-ALAS induction to occur, e.g. upon glucocorticoid induction of TDO during fasting (starvation) and exogenous glucocorticoid administration. Currently, glucose therapy is the preferred strategy for reversing moderate attacks induced by fasting (calorie restriction), with more severe attacks being treated by intravenous heme preparations. Reversal of fasting-induced attacks by glucose is explained by the previously demonstrated reversal of increased heme utilisation by TDO. Inhibitors of this utilisation are therefore potential therapeutic targets in acute attacks and also for maintenance of a symptomless state. Existing TDO inhibitors other than glucose include allopurinol, nicotinamide and recently developed potent inhibitors such as LM10 used in cancer therapy. Based on studies in rats, the hypothesis predicts that the safety or otherwise of drugs in the hepatic porphyrias is determined by their ability to inhibit TDO utilisation of heme under basal conditions or after glucocorticoid induction or heme activation of TDO, in parallel with reciprocal changes in 5-ALAS induction. Tryptophan is also proposed as a potential therapy of acute attacks either alone or as an adjunct to the recently proposed 5-ALAS1 gene silencing. Trp increases heme biosynthesis by enhancing 5-ALA dehydratase activity and, based on a Trp-5-ALA model presented herein, Trp offers several advantages over heme therapy, namely rapid conversion of 5-ALA into heme, a greatly enhanced heme availability, a near complete inhibition of 5-ALAS induction, assumed rapid clearance of 5-ALA and hence accelerated resolution of symptoms of attacks, and finally provision of the neuroprotective metabolite kynurenic acid to neutralise the neurological symptoms. The hypothesis also addresses heme regulation in species lacking the TDO free apoenzyme and its glucocorticoid induction mechanism and proposes detailed assessment of heme biosynthesis in these species. Detailed proposals for testing the hypothesis are presented.

Negative effects on newborn piglets caused by excess dietary tryptophan in the morning in sows.

BACKGROUND: This study investigated the effect of dynamic feeding models of dietary tryptophan on sows' performance during late pregnancy. RESULTS: The average piglet birth weight and live farrowing rate from sows consuming a high-low tryptophan diet (0.39% Trp in the morning and 0.13% Trp in the afternoon) were decreased compared with those fed a 2×tryptophan diet (0.26% Trp in the morning and afternoon). Compared with the 2×tryptophan group, sow serum kynurenic acid and the newborn liver n-6:n-3 polyunsaturated fatty acid ratio were significantly higher, and sow serum taurine and newborn serum taurine, phosphoserine, cysteine and proline were lower in the high-low tryptophan diet group. Eighty-eight genes were differentially expressed in newborn piglets' livers between the 2×tryptophan and high-low groups. Genes related to cytotoxic effector regulation (major histocompatibility complex class I proteins), NADH oxidation, reactive oxygen species (ROS) metabolism and tissue development were differentially expressed between these two groups. CONCLUSION: Together, the results provide information on new biomarkers in serum or liver and provide novel insights into variations in the fetal liver during exogenous stimulus response and biological processes of ROS metabolism in fetuses during late pregnancy caused by a single excessive tryptophan ingestion daily in the morning. © 2018 Society of Chemical Industry.

Macimorelin as a Diagnostic Test for Adult GH Deficiency.

Purpose: The diagnosis of adult GH deficiency (AGHD) is challenging and often requires confirmation with a GH stimulation test (GHST). The insulin tolerance test (ITT) is considered the reference standard GHST but is labor intensive, can cause severe hypoglycemia, and is contraindicated for certain patients. Macimorelin, an orally active GH secretagogue, could be used to diagnose AGHD by measuring stimulated GH levels after an oral dose. Materials and Methods: The present multicenter, open-label, randomized, two-way crossover trial was designed to validate the efficacy and safety of single-dose oral macimorelin for AGHD diagnosis compared with the ITT. Subjects with high (n = 38), intermediate (n = 37), and low (n = 39) likelihood for AGHD and healthy, matched controls (n = 25) were included in the efficacy analysis. Results: After the first test, 99% of macimorelin tests and 82% of ITTs were evaluable. Using GH cutoff levels of 2.8 ng/mL for macimorelin and 5.1 ng/mL for ITTs, the negative agreement was 95.38% (95% CI, 87% to 99%), the positive agreement was 74.32% (95% CI, 63% to 84%), sensitivity was 87%, and specificity was 96%. On retesting, the reproducibility was 97% for macimorelin (n = 33). In post hoc analyses, a GH cutoff of 5.1 ng/mL for both tests resulted in 94% (95% CI, 85% to 98%) negative agreement, 82% (95% CI, 72% to 90%) positive agreement, 92% sensitivity, and 96% specificity. No serious adverse events were reported for macimorelin. Conclusions: Oral macimorelin is a simple, well-tolerated, reproducible, and safe diagnostic test for AGHD with accuracy comparable to that of the ITT. A GH cutoff of 5.1 ng/mL for the macimorelin test provides an excellent balance between sensitivity and specificity.

Dietary Tryptophan Restriction Dose-Dependently Modulates Energy Balance, Gut Hormones, and Microbiota in Obesity-Prone Rats.

OBJECTIVE: To determine the effects of graded dietary restriction of tryptophan on food intake, energy expenditure, body composition, gut hormones, and select fecal bacterial populations in obesity-prone rats. METHODS: Obesity-prone rats were randomized to isocaloric diets with varying degrees of tryptophan restriction: control (100% requirements), 70% tryptophan (70TRP), 40% tryptophan (40TRP), or 10% tryptophan (10TRP) for 21 days. The sympathetic system was challenged with a subcutaneous injection of propranolol on days 15 to 17. Measurements included food intake, energy expenditure, body composition, metabolic hormones, and fecal concentrations of select bacteria. RESULTS: Moderate tryptophan restriction (70TRP) induced thermogenesis without altering body composition, whereas severe degrees of restriction (40TRP, 10TRP) produced profound hypophagia and decreased energy expenditure and body weight. The thermogenic effects of moderate tryptophan restriction were sympathetically mediated. Severe tryptophan restriction decreased fasting circulating concentrations of glucose, insulin, C-peptide, and leptin, but increased glucagon, pancreatic polypeptide, and glucagon-like peptide-1. Severe tryptophan restriction decreased fecal concentrations of Enterobacteriaceae, Lactobacillus, Bacteroides, and Clostridium coccoides while increasing Roseburia groups. CONCLUSIONS: Our findings demonstrate that dietary tryptophan restriction dose-dependently modulates energy balance, with severe restriction causing hypophagia and weight loss and moderate restriction promoting sympathetically driven thermogenesis as well as concurrent changes in gut microbiota and hormones.

A phase I study of indoximod in patients with advanced malignancies.

PURPOSE: Indoximod is an oral inhibitor of the indoleamine 2,3-dioxygenase pathway, which causes tumor-mediated immunosuppression. Primary endpoints were maximum tolerated dose (MTD) and toxicity for indoximod in patients with advanced solid tumors. Secondary endpoints included response rates, pharmacokinetics, and immune correlates. EXPERIMENTAL DESIGN: Our 3+3 phase I trial comprised 10 dose levels (200, 300, 400, 600, and 800 mg once/day; 600, 800, 1200, 1600, and 2000 mg twice/day). Inclusion criteria were measurable metastatic solid malignancy, age ≥18 years, and adequate organ/marrow function. Exclusion criteria were chemotherapy ≤ 3 weeks prior, untreated brain metastases, autoimmune disease, or malabsorption. RESULTS: In 48 patients, MTD was not reached at 2000 mg twice/day. At 200 mg once/day, 3 patients previously treated with checkpoint inhibitors developed hypophysitis. Five patients showed stable disease >6 months. Indoximod plasma AUC and Cmax plateaued above 1200mg. Cmax (~12 µM at 2000 mg twice/day) occurred at 2.9 hours, and half-life was 10.5 hours. C reactive protein (CRP) levels increased across multiple dose levels. CONCLUSIONS: Indoximod was safe at doses up to 2000 mg orally twice/day. Best response was stable disease >6 months in 5 patients. Induction of hypophysitis, increased tumor antigen autoantibodies and CRP levels were observed.

Ação de metabólitos da via das triptaminas em linhagens de melanomas / Action of tryptamines pathway metabolites in melanoma strains

O triptofano (Trp) é essencial para muitos processos fisiológicos e seu metabolismo apresenta-se alterado em doenças como no câncer. O Trp é degradado por três vias: via das quinureninas; via serotonérgica e via das triptaminas. A primeira está envolvida com a tolerância e o imune escape de células tumorais, já a segunda leva a produção de serotonina e melatonina, com uma diversidade de funções biológicas e que possuem atividades antitumorais reconhecidas. A terceira rota é a menos estudada e a função dos compostos sintetizados ainda é desconhecida. Trabalhos do grupo mostram que a via das triptaminas é ativa em melanomas e que triptamina (TRY) e dimetiltriptamina (DMT), metabólitos produzidos por esta via, também possuem atividade antitumoral. Nosso objetivo é avançar sobre a compreensão de como esta via afeta o metabolismo e crescimento tumoral. Para tanto, estudamos mais detalhadamente a via em linhagens de melanoma. A adição de TRY e DMT nas culturas modificou a produção de compostos das outras rotas de metabolização do Trp. Além disso, TRY e DMT afetaram a invasividade das células tumorais e TRY aumentou a atividade citotóxica de células mononucleares frente a melanomas. Observamos que apesar dos efeitos biológicos da via das quinureninas estar amplamente relacionado a ligação dos metabólitos no receptor de aril hidrocarbonetos, para a via das triptaminas o receptor parece não estar associado com a atividade antitumoral descrita. Nossos resultados apontam para a importância da via das triptaminas na dinâmica tumoral e a necessidade de estudos mais amplos relacionados ao metabolismo do Trp

Tryptophan (Trp) is essential for many physiological processes and its metabolism is modified in several diseases such as in cancer. TRP is broken down into three pathways: kynurenine path, serotonergic path and tryptamine path. The first is involved in tolerance and immune escape of cancer cells, while the second leads to the production of serotonin and melatonin, which have a variety of biological functions and recognized antitumor activity. The third route is the least studied and the biological function of the synthesized compounds is still unknown. Our group shows that tryptamine path is active in melanomas and tryptamine (TRY) and dimethyltryptamine (DMT), metabolites produced by this route, also have antitumor activity. Our goal is make progress on understanding how tryptamine route affects metabolism and tumor growth. Therefore, we studied in detail this pathway in melanoma cell lines. The addition of TRY and DMT into the cultures leds the production of metabolites of other Trp routes. Moreover, TRY and DMT affect the invasiveness of tumor cells and TRY increased antitumor activity of the immune system against melanomas. We observed that despite biological effects of kynurenine path be largely related to metabolites binding aryl hydrocarbon receptor, for tryptamine pathway the receptor seems not to be associated with the described antitumor activity. Our results point the importance of tryptamine pathway in tumor dynamics and the need for broader studies related to Trp metabolism

Tryptophan-induced pathogenesis of breast cancer.

BACKGROUND: The pathogenesis of breast cancer remains unclear. AIMS: To investigate the pathogenesis of breast cancer through targeted metabolomics of amino acids components in serum of patients with breast cancer. METHODS: Patients with breast cancers were enrolled in our hospital between year January 1(st), 2013 and December 31(st), 2014. Targeted analysis of amino acids was performed using ESI-QTOF-MS instrument. In vitro experiment was performed to determine the influence of tryptophan towards interleukin-10 (IL-10) secretion by CD4+ T cell. RESULTS: Targeted metabolomics of amino acids showed that the level of tryptophan significantly (p<0.05) increased in patients with breast cancer. Furthermore, the biological function of tryptophan was determined through determining the influence of tryptophan towards IL-10 secretion using in vitro method. The addition of tryptophan (100 uM) in the cell medium can significantly inhibited the secretion of IL-10 by CD4+ T cells, as indicated by the mRNA level and protein concentration. CONCLUSION: The inhibition of IL-10 secretion by CD4+ T cells is a potential pathogenesis of breast cancer.

Ultrasound imaging of fasciitis due to body-building supplement.

BACKGROUND: Fascia and soft tissues, rich in collagen, receptors of pain and capable of significant distention, may be targets of autoimmune inflammatory diseases. We observed fasciitis due to the protein supplement Pure Whey, which has not been reported previously. METHODS: Sonography (Sonosite-Titan, 5 to 10 MHz, L-38) was performed on a patient (age, 26 years; body mass index, 38 kg/m2) with protein fasciitis. He had developed compact swelling of his forearms, hands, and legs, with skin irregularity and severe disability (without peripheral eosinophilia, normal Ig and ESR 18/hr) after taking Pure Whey, containing L-tryptophan (1.4 g per 100 g of protein). A deep skin biopsy was performed. The thickness of the brachioradial fascia (BRF) was measured and compared with 10 healthy control subjects (men ages 36.7 +/- 8.3 years; body mass index, 26.4 +/- 6.5 kg/m2). RESULTS: The deep skin biopsy showed severe fat interlobular and fascial thickening with mononuclear (noneosinophilic) infiltrate and fibrosis associated with fasciitis. BRF of the 10 healthy men had a thickness of 0.75 +/- 0.19 mm, compared with the patient's 2.4 mm thickened and cleaved BRF. After 2.5 months of corticosteroid therapy (30 mg/d with tapering) and discontinuation of the protein supplement, the patient's BRF returned to a monolayer appearance. Its thickness reduced to normal (0.8 mm), with significant clinical improvement. CONCLUSIONS: This case of noneosinophilic fasciitis associated with ingestion of L-tryptophan-containing protein supplement responded favorably to corticosteroid therapy. Sonography proved to be an effective method to visualize and confirm the fasciitis and to follow the course and therapy.

Insuficiência respiratória aguda como manifestação da síndrome de eosinofilia-mialgia associada à ingestão de L-triptofano / Acute respiratory failure as a manifestation of eosinophilia-myalgia syndrome associated with L-tryptophan intake

A síndrome da eosinofilia-mialgia foi descrita em 1989 em pacientes que apresentavam mialgia progressiva e incapacitante e eosinofilia sérica, nos líquidos e secreções. A maioria dos pacientes relatava uso prévio de L-triptofano. Sintomas respiratórios são relatados em até 80 por cento dos casos, eventualmente como manifestação única. O tratamento inclui suspensão da droga e corticoterapia. Relatamos o caso de uma mulher de 61 anos com insuficiência respiratória aguda após uso de L-triptofano, hidroxitriptofano e outras drogas. A paciente apresentava eosinofilia no sangue, lavado broncoalveolar e derrame pleural. Após a suspensão da medicação e corticoterapia, houve melhora clínica e radiológica em poucos dias.

Eosinophilia-myalgia syndrome was described in 1989 in patients who presented progressive and incapacitating myalgia and eosinophilia in blood, fluids and secretions. Most patients report previous L-tryptophan intake. Respiratory manifestations are found in up to 80 percent of the cases, occasionally as the only manifestation. Treatment includes drug discontinuation and administration of corticosteroids. Here, we describe the case of a 61-year-old female admitted with acute respiratory failure after using L-tryptophan, hydroxytryptophan and other drugs. The patient presented eosinophilia, together with elevated eosinophil counts in the bronchoalveolar lavage and pleural effusion. After discontinuation of the drugs previously used, corticosteroids were administered, resulting in clinical and radiological improvement within just a few days.

Effect of tryptophan depletion on smokers and nonsmokers with and without history of major depression.

BACKGROUND: Serotonergic dysregulation is posited to contribute to comorbidity between nicotine dependence and depression. We tested whether acute tryptophan depletion (ATD) triggers depressive symptoms in euthymic, unmedicated smokers and nonsmokers with and without history of major depressive disorder (MDD). METHODS: Acute tryptophan depletion and taste-matched placebo challenges were administered double-blind in counter-balanced order. Participants were four groups of volunteers hypothesized to be of increasing affective vulnerability as follows: nonsmokers lacking recurrent personal and familial history of MDD (n = 20), smokers lacking recurrent personal and familial history of MDD (n = 21), nonsmokers with history of recurrent personal and familial MDD (n = 16), and smokers with recurrent personal and familial history of MDD (n = 16). Depression, dysphoric mood, and plasma amino acids were measured at baseline and around the time of peak depletion. RESULTS: Depressive symptom response to ATD was heightened significantly by history of MDD (p < .001) and marginally by smoking (p = .09). Smoking seemed to magnify the ATD response of those with a history of MDD (effect size = .63) but had no effect on those without MDD history (effect size = .06). CONCLUSIONS: Depressive symptom response to serotonergic challenge is exaggerated in unmedicated, euthymic adults with recurrent personal and familial vulnerability to MDD, perhaps especially if they also smoke.

Calcinosis cutis in a patient with eosinophilia-myalgia syndrome: case report.

Eosinophilia-myalgia syndrome (EMS) often is a disabling disorder caused by the consumption of contaminated L-tryptophan. Affected patients present with an array of symptoms, including cutaneous manifestations, peripheral eosinophilia, myalgias, and long-term neurocognitive disability. This article is the first reported case of a patient with EMS who developed calcinosis cutis. While many long-term sequelae of EMS are reported in the literature, there are no reports of the development of dystrophic calcification in these patients. The calcinosis cutis in this patient with EMS may represent a new manifestation of EMS that has not been documented to date. If more patients with EMS develop calcinosis cutis, it will present a therapeutic challenge to the physicians managing these patients.

Risk factors for pulmonary arterial hypertension.

The present limitations in knowledge of the potential risk factors for PPH undoubtedly are attributable to the facts that PPH is a rare disease with an unknown pathogenesis and lacking large case series. Moreover, definite epidemiologic data are rare and ideally should be obtained from epidemiologic surveys such as large case-control studies. The increased incidence of the disease in young women, the familial cases, the association with autoimmune disorders, and the recent discovery that mutation of the PPH1 gene may not be restricted to familial PPH support the hypothesis that the development of pulmonary hypertension likely implies an individual susceptibility or predisposition, which is probably genetically determined. It is also now commonly believed that the development of pulmonary hypertension in some of these predisposed individuals could be hastened or precipitated by various expression factors (some of them yet unrecognized), such as ingestion of certain drugs or diets, portal hypertension, or HIV infection.

Epidemics of vascular toxicity and pulmonary hypertension: what can be learned?

Epidemics of vascular disease caused by toxins and infectious agents affecting both humans and animals have been common in history. Examples of agents implicated include anorexients, ergotamine, mercury, arsenic, vinyl chloride, thorotrast, plant alkaloids, nitrites, toxic oil, tryptophan and bacterial, viral and parasitic infections. A major characteristic of these disorders is endothelial dysfunction, which may manifest itself in vasospastic disorders, sclerodermiform skin lesions, fibrosis, osteolytic lesions, polyneuropathy and portal and pulmonary hypertension. Angiosarcoma may also be a late outcome. These diseases are more common than is generally appreciated. The aetiology is usually multifactorial. This and other factors contribute to delayed recognition.