5-methoxytryptophan is a potential marker for post-myocardial infarction heart failure - a preliminary approach to clinical utility

Predictive Value of 5-Methoxytryptophan on Long-Term Clinical Outcome after PCI in Patients with Acute Myocardial Infarction-a Prospective Cohort Study

BACKGROUND

In recent years, 5-Methoxytryptophan (5-MTP) has been identified as an endothelial factor with vaso-protective and anti-inflammatory properties.

METHODS

In this prospective cohort study, a total of 407 patients with acute myocardial infarction (AMI) who underwent percutaneous coronary intervention (PCI) successfully were enrolled. A 1-year follow-up Kaplan-Meier survival analysis was used for evaluating the correlation between 5-MTP and major adverse cardiovascular event (MACE) while Cox proportional-hazards regression was used to identify predictive values of 5-MTP on MACE after AMI.

RESULTS

Increased 5-MTP level led to a significant downtrend in the incidence of MACE (All Log-rank p < 0.05). Thus, a high baseline 5-MTP could reduce the 1-year incidence of MACE (HR = 0.33, 95%Cl 0.17-0.64, p = 0.001) and heart failure (HF) (HR = 0.28, 95% Cl 0.13-0.62, p = 0.002). Subgroup analysis indicated the predictive value of 5-MTP was more significant in patients aged ≤ 65 years and those with higher baseline NT-proBNP, T2DM, STEMI, and baseline HF with preserved LVEF (HFpEF) characteristics.

CONCLUSIONS

Plasma 5-MTP is an independent and protective early biomarker for 1-year MACE and HF events in patients with AMI, especially in younger patients and those with T2DM, STEMI, and baseline HFpEF characteristics.

Characterization of LC-MS based urine metabolomics in healthy children and adults

Previous studies reported that sex and age could influence urine metabolomics, which should be considered in biomarker discovery. As a consequence, for the baseline of urine metabolomics characteristics, it becomes critical to avoid confounding effects in clinical cohort studies. In this study, we provided a comprehensive lifespan characterization of urine metabolomics in a cohort of 348 healthy children and 315 adults, aged 1 to 78 years, using liquid chromatography coupled with high resolution mass spectrometry. Our results suggest that sex-dependent urine metabolites are much greater in adults than in children. The pantothenate and CoA biosynthesis and alanine metabolism pathways were enriched in early life. Androgen and estrogen metabolism showed high activity during adolescence and youth stages. Pyrimidine metabolism was enriched in the geriatric stage. Based on the above analysis, metabolomic characteristics of each age stage were provided. This work could help us understand the baseline of urine metabolism characteristics and contribute to further studies of clinical disease biomarker discovery.

Restoration of 5-methoxytryptophan protects against atherosclerotic chondrogenesis and calcification in ApoE-/- mice fed high fat diet

Background

Toll-like receptor-2 (TLR2) promotes vascular smooth muscle cell (VSMC) transdifferentiation to chondrocytes and calcification in a p38 MAPK-dependent manner. Vascular 5-methoxytryptophan (5-MTP) is a newly identified factor with anti-inflammatory actions. As 5-MTP targets p38 MAPK for its actions, we postulated that 5-MTP protects against vascular chondrogenesis and calcification.

Methods

High-fat diet-induced advanced atherosclerosis in mice were performed to investigate the effect of 5-MTP on atherosclerotic lesions and calcification. VSMCs were used to determine the role of 5-MTP in VSMC chondrogenic differentiation and calcification. Alizarin red S and Alcian blue staining were used to measure VSMC calcification and chondrogenic differentiation, respectively.

Results

5-MTP was detected in aortic tissues of ApoE^−/− mice fed control chow. It was reduced in ApoE^−/− mice fed high-fat diet (HFD), but was restored in ApoE^−/−Tlr2^−/− mice, suggesting that HFD reduces vascular 5-MTP production via TLR2. Intraperitoneal injection of 5-MTP or its analog into ApoE^−/− mice fed HFD reduced aortic atherosclerotic lesions and calcification which was accompanied by reduction of chondrogenesis and calcium deposition. Pam3CSK4 (Pam3), ligand of TLR2, induced SMC phenotypic switch to chondrocytes. Pretreatment with 5-MTP preserved SMC contractile proteins and blocked Pam3-induced chondrocyte differentiation and calcification. 5-MTP inhibited HFD-induced p38 MAPK activation in vivo and Pam3-induced p38 MAPK activation in SMCs. 5-MTP suppressed HFD-induced CREB activation in aortic tissues and Pam3-induced CREB and NF-κB activation in SMCs.

Conclusions

These findings suggest that 5-MTP is a vascular arsenal against atherosclerosis and calcification by inhibiting TLR2–mediated SMC phenotypic switch to chondrocytes and the consequent calcification. 5-MTP exerts these effects by blocking p38 MAPK activation and inhibiting CREB and NF-κB transactivation activity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-021-00771-1.

5-Methoxytryptophan attenuates postinfarct cardiac injury by controlling oxidative stress and immune activation

AIMS

Myocardial infarction (MI) remains a major cause of heart failure. 5-Methoxytryptophan (5-MTP), a 5-methoxyindole metabolite of L-tryptophan, exerts anti-inflammatory and antifibrotic effects, but MI impairs the biosynthesis of cardiac 5-MTP. Therefore, we evaluated the effect of exogenous 5-MTP administration on rescuing post-MI cardiac injury.

METHODS AND RESULTS

After a detailed pharmacokinetic analysis of 5-MTP, Sprague Dawley rats that had undergone left anterior descending coronary artery ligation received intraperitoneal administration of either 17 mg/kg 5-MTP or saline at 0.5 and 24 h after MI. Cardiac systolic function, infarction size, and fibrosis were evaluated using echocardiography, triphenyltetrazolium chloride staining, and Masson trichrome staining, respectively. Myocardial apoptosis was analyzed by staining for caspase-3 and cardiac troponin I. 5-MTP treatment decreased the infarct area and myocardial apoptosis; attenuated systolic dysfunction and left ventricular dilatation; and reduced cardiomyocyte hypertrophy, myocardial fibrosis, and infarct expansion. Crucially, 5-MTP alleviated oxidative stress by preserving mitochondrial antioxidant enzymes and downregulating reactive oxygen species-generating NADPH oxidase isoforms and endothelin-1. Consequently, 5-MTP-treated MI rat hearts exhibited lower levels of chemokines and cytokines, namely interleukin (IL)-1β, IL-18, IL-6, C-C motif chemokine ligand (CCL)-2, and CCL5, accompanied by reduced infiltration of CD11b⁺ cells and CD4⁺ T cells. Notably, 5-MTP protected against H₂O₂-induced damage in HL-1 cardiomyocytes and human umbilical vein endothelial cells in vitro.

CONCLUSION

5-MTP prevented post-MI cardiac injury by promoting mitochondrial stabilization and controlling redox imbalance. This cytoprotective effect ameliorated macrophage and T-cell infiltration, thus reducing the infarct size, attenuating fibrosis, and restoring myocardial function.

5-methoxytryptophan: an arsenal against vascular injury and inflammation

5-methoxytryptophan (5-MTP) is an endothelial factor with anti-inflammatory properties. It is synthesized from L-tryptophan via two enzymatic steps: tryptophan hydroxylase-1 (TPH-1) and hydroxyindole O-methyltransferase. Lipopolysaccharide (LPS) and pro-inflammatory cytokines suppress endothelial 5-MTP production by inhibiting TPH-1 expression. 5-MTP protects endothelial barrier function and promotes endothelial repair, while it blocks vascular smooth muscle cell migration and proliferation by inhibiting p38 MAPK activation. 5-MTP controls macrophage transmigration and activation by inhibiting p38 MAPK and NF-κB activation. 5-MTP administration attenuates arterial intimal hyperplasia, defends against systemic inflammation and prevents renal fibrosis in relevant murine models. Serum 5-MTP level is depressed in human sepsis as well as in mice with sepsis-like disorder. It is reduced in chronic kidney disease and acute myocardial infarction in humans. The reported data suggest that serum 5-MTP may be a theranostic biomarker. In summary, 5-MTP represents a new class of tryptophan metabolite which defends against inflammation and inflammation-mediated tissue damage and fibrosis. It may be a valuable lead compound for developing new drugs to treat complex human inflammatory disorders.

An Integrated Lipidomics and Phenotype Study Reveals Protective Effect and Biochemical Mechanism of Traditionally Used Alisma orientale Juzepzuk in Chronic Kidney Disease

Alisma orientale Juzepzuk (AO) is widely used for various diuretic and nephropathic treatments in traditional Chinese medicines (TCM). In a clinical setting, AO is used as both a lipid-lowering and tubular interstitial fibrosis agent. However, the mechanisms of AO for the treatment of renal interstitial fibrosis and abnormal lipid metabolism are not well-understood. In this study, pharmacological and UPLC-HDMS-based lipidomic approaches were employed to investigate the lipid-lowering and tubular interstitial fibrosis effect of AO on rats with adenine-induced chronic kidney disease (CKD). Rats with CKD showed increased serum levels of creatinine and urea, tubular damage, and tubular interstitial fibrosis. Moreover, multiple lipid species were identified in CKD rats. Among these lipids, polyunsaturated fatty acid, eicosapentaenoic acid, 8,9-epoxyeicosatrienoic acid, and docosahexaenoic acid levels were significantly decreased in CKD rats compared to control rats. In CKD rats, up-regulation of the NF-κB pathway may impair polyunsaturated fatty acid metabolism, causing renal fibrosis. In addition, CKD rats showed significantly decreased diglyceride levels and increased triglyceride levels compared to the control group. Pathway over-representation analysis demonstrated that 30 metabolic pathways were associated with lipid species. AO treatment suppressed up-regulation of inflammation, and partly restored the deregulation of polyunsaturated fatty acids and glycerolipids metabolism. Our results indicated that AO treatment attenuated renal fibrosis by down-regulating inflammation, and mitigating lipid metabolism in CKD rats. In conclusion, this study has identified the therapeutic lipid-lowering and anti-fibrosis effects of AO on CKD.