Association Between Plasma Trimethylamine N-oxide and Neoatherosclerosis in Patients With Very Late Stent Thrombosis

The gut microbiota in thrombosis

The gut microbiota has emerged as an environmental risk factor that affects thrombotic phenotypes in several cardiovascular diseases. Evidence includes the identification of marker species by sequencing studies of the gut microbiomes of patients with thrombotic disease, the influence of antithrombotic therapies on gut microbial diversity, and preclinical studies in mouse models of thrombosis that have demonstrated the functional effects of the gut microbiota on vascular inflammatory phenotypes and thrombus formation. In addition to impaired gut barrier function promoting low-grade inflammation, gut microbiota-derived metabolites have been shown to act on vascular cell types and promote thrombus formation. Therefore, these meta-organismal pathways that link the metabolic capacities of gut microorganisms with host immune functions have emerged as potential diagnostic markers and novel drug targets. In this Review, we discuss the link between the gut microbiota, its metabolites and thromboembolic diseases.

Dysfunction of cecal microbiota and CutC activity in mice mediating diarrhea with kidney-yang deficiency syndrome

Objective

Previous studies have indicated that diarrhea with kidney-yang deficiency syndrome leads to a disorder of small intestine contents and mucosal microbiota. However, the relationship of TMA-lyase (CutC) activity and TMAO with diarrhea with kidney-yang deficiency syndrome remains unexplored. Therefore, this study explores the relationship between cecal microbiota and choline TMA-lyase (CutC) activity, as well as the correlation between trimethylamine oxide (TMAO), inflammatory index, and CutC activity.

Method

Twenty SPF-grade male KM mice were randomly divided into the normal group (CN) and the diarrhea model group (CD). Diarrhea mouse models were established by adenine combined with Folium sennae administration. CutC activity, TMAO, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) levels were detected, and the cecal content microbiota was sequenced.

Result

After 14 days, diarrhea occurred in the CD group. Compared with the CN group, there was no significant change in the activity of CutC in the small intestine of the CD group, while the activity of CutC in the cecum was significantly increased, and the levels of TMAO, IL-6, and TNF-α showed a significant increase. The Chao1 index, Observed_species index, Shannon index, and Simpson index all exhibited a decreasing trend. The main changes at the bacterial genus level were Alistipes, Enterorhabdus, Desulfovibrio, Bacteroides, Candidatus_Saccharimonas, and [Ruminococcus]_torques_group. The results of LEfSe analysis, random forest analysis and ROC curve analysis revealed Paludicola, Blautia, Negativibacillus, Paraprevotella, Harryflintia, Candidatus_Soleaferrea, Anaerotruncus, Oscillibacter, Colidextribacter, [Ruminococcus]_torques_group, and Bacteroides as characteristic bacteria in the CD group. Correlation analysis showed a significant negative correlation between cecal CutC activity and Ligilactobacillus, and a significant positive correlation with Negativibacillus and Paludicola. The level of TMAO was significantly positively correlated with CutC activity and IL-6.

Conclusion

Diarrhea with kidney-yang deficiency syndrome significantly affects the physiological status, digestive enzyme activity, CutC activity, TMAO levels, and inflammatory response in mice. Additionally, there are changes in the composition and function of cecal microbiota, indicating an important impact of diarrhea with kidney-yang deficiency syndrome on the host intestinal microbiota balance. The occurrence of diarrhea with kidney-yang deficiency syndrome may be associated with dysbiosis of intestinal microbiota, increased CutC activity, elevated TMAO levels, and heightened inflammatory factor levels.

Trimethylamine-N-oxide (TMAO) promotes balloon injury-induced neointimal hyperplasia via upregulating Beclin1 and impairing autophagic flux

BACKGROUND AND AIMS

TMAO is a microbiota-dependent metabolite associated with increased risk of various cardiovascular diseases. However, the relationship between TMAO and vascular injury-related neointimal hyperplasia is unclear. This study aimed to explore whether TMAO promotes neointimal hyperplasia after balloon injury and elucidate the underlying mechanism.

METHODS AND RESULTS

Through hematoxylin and eosin staining and immunohistochemistry staining, we found that supplementary TMAO promoted balloon injury-induced neointimal hyperplasia, while reducing TMAO by antibiotic administration produced the opposite result. TMAO showed limited effect on rat aortic vascular smooth muscle cells (RAOSMCs) proliferation and migration. However, TMAO notably induced dysfunction of rat aortic vascular endothelial cells (RAOECs) in vitro and attenuated reendothelialization of carotid arteries after balloon injury in vivo. Autophagic flux was measured by fluorescent mRFP-GFP-LC3, transmission electron microscopy, and western blot. TMAO impaired autophagic flux, as evidenced by the accumulation of p62 and LC3II and high autophagosome to autolysosome ratios. Furthermore, we confirmed that Beclin1 level increased in TMAO-treated RAOECs and carotid arteries. Knocking down Beclin1 alleviated TMAO-induced autophagic flux impairment and neointimal hyperplasia.

CONCLUSIONS

TMAO promoted neointimal hyperplasia through Beclin1-induced autophagic flux blockage, suggesting that TMAO is a potential target for improvement of vascular remodeling after injury.

Culprit-Plaque Morphology and Residual SYNTAX Score Predict Cardiovascular Risk in Acute Myocardial Infarction: An Optical Coherence Tomography Study

AIMS

Culprit-plaque morphology [plaque rupture (PR) and plaque erosion (PE)] and high-risk plaques (HRP) identified by optical coherence tomography (OCT) and residual SYNTAX score (rSS) have been reported to influence clinical outcomes. Thus, in this study, we aimed to investigate the prognostic implication of culprit-plaque morphology and rSS for major adverse cardiovascular events (MACE) in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS

Based on plaque morphology and rSS, 274 STEMI patients were divided into 4 groups: PE/low-rSS (n=61), PE/high-rSS (n=58), PR/low-rSS (n=55), and PR/high-rSS (n=100). According to HRP and rSS, patients were stratified to non-HRP/low-rSS (n=97), non-HRP/high-rSS (n=109), HRP/low-rSS (n=19), and HRP/high-rSS (n=49). MACE was defined as the composite of all-cause death, recurrence of myocardial infarction, stroke, and unplanned revascularization of any coronary artery.

RESULTS

During the follow-up of 2.2 years, 47 (17.2%) MACE were observed. Patients with PR/high-rSS and HRP/high-rSS presented lower survival probability on revascularization and MACE. In fully adjusted analyses, PR/high-rSS group presented higher MACE risk than PE/low-rSS (HR: 4.80, 95% CI: 1.43-16.11, P=0.025). Patients with non-HRP/high-rSS (HR: 2.90, 95% CI: 1.01-8.38, P=0.049) and HRP/high-rSS (HR: 8.67, 95% CI: 2.67-28.21, P＜0.001) presented higher risk of cardiac events than non-HRP/low-rSS. Adding rSS and HRP to the risk prediction model increased the C-statistic to 0.797 (95% CI: 0.737-0.857), with ΔC-statistic of 0.066 (P=0.002) and the NRI (46.0%, 95% CI: 20.5-56.8%, P＜0.001) and IDI (8.7%, 95% CI: 3.6-18.2%, P＜0.001).

CONCLUSION

High-risk plaques in combination with rSS enhanced the predictive ability for MACE, indicating culprit-plaque features and residual atherosclerosis burden should be taken into account in risk stratification of STEMI patients.

Prognostic value of plasma phenylalanine and gut microbiota-derived metabolite phenylacetylglutamine in coronary in-stent restenosis

Objective

This study was designed to explore the predictive value of plasma phenylalanine (Phe) and gut microbiota-derived metabolite phenylacetylglutamine (PAGln) in coronary in-stent restenosis (ISR).

Methods

Patients with coronary ISR, in-stent hyperplasia (ISH), and in-stent patency (ISP) were retrospectively enrolled in this study. Multivariable logistic regression analyses were used to identify independent risk factors of ISR. The predictive value of plasma Phe and PAGln levels was evaluated by receiver operating characteristic (ROC) curve analysis. The areas under the ROC curve (AUCs) were compared using the Z-test. The correlation between PAGln and clinical characteristics were examined using Spearman's correlation analysis.

Results

Seventy-two patients (mean age, 64.74 ± 9.47 years) were divided into three groups according to coronary stent patency: ISR (n = 28), ISH (n = 11), and ISP (n = 33) groups. The plasma levels of Phe and PAGln were significantly higher in the ISR group than in the ISP group. PAGln was positively associated with the erythrocyte sedimentation rate, homocysteine, SYNTAX score, triglyceride to high-density lipoprotein ratio, Phe, and microbiota-related intermediate metabolite phenylacetic acid (PA). In the ISR group, with the aggravation of restenosis, PAGln levels were also elevated. In multivariate regression analyses, Phe, PAGln and SYNTAX score were independent predictors of coronary ISR (all P < 0.05). In the ROC curve analyses, both Phe [AUC = 0.732; 95% confidence interval (CI), 0.606–0.858; P = 0.002] and PAGln (AUC = 0.861; 95% CI, 0.766–0.957; P < 0.001) had good discrimination performance in predicting coronary ISR, and the predictive power of PAGln was significantly better (P = 0.031).

Conclusion

Plasma Phe and PAGln are valuable indices for predicting coronary ISR, and gut microbes may be a promising intervention target to prevent ISR progression.

Gut microbiota in sarcopenia and heart failure

Sarcopenia is common in aging and in patients with heart failure (HF) who may experience worse outcomes. Patients with muscle wasting are more likely to experience falls and can have serious complications when undergoing cardiac procedures. While intensive nutritional support and exercise rehabilitation can help reverse some of these changes, they are often under-prescribed in a timely manner, and we have limited insights into who would benefit. Mechanistic links between gut microbial metabolites (GMM) have been identified and may contribute to adverse clinical outcomes in patients with cardio-renal diseases and aging. This review will examine the emerging evidence for the influence of the gut microbiome-derived metabolites and notable signaling pathways involved in both sarcopenia and HF, especially those linked to dietary intake and mitochondrial metabolism. This provides a unique opportunity to gain mechanistic and clinical insights into developing novel therapeutic strategies that target these GMM pathways or through tailored nutritional modulation to prevent progressive muscle wasting in elderly patients with heart failure.

High-Risk Culprit Plaque Predicts Cardiovascular Outcomes Independently of Plaque Rupture in ST-Segment Elevation Myocardial Infarction: Insight From Optical Coherence Tomography

The present study explored the predictive value of culprit high-risk plaque (HRP) detected by optical coherence tomography (OCT) for predicting major adverse cardiovascular events (MACEs) in patients with ST-segment elevation myocardial infarction (STEMI). HRP was defined as the simultaneous presence of four criteria: minimum lumen area <3.5 mm², fibrous cap thickness <75 μm, lipid plaque with lipid arc extension >180°, and presence of macrophages. Patients (n = 274) were divided into non-HRP group (n = 206) and HRP group (n = 68). MACEs were defined as a composite of all-cause death, myocardial infarction, stroke, and revascularization. During a mean follow-up of 2.2 years, 47 (17.5%) MACEs were observed: 28 (13.6%) in the non-HRP group and 19 (27.9%) in the HRP group (log-rank P = .005). Patients with HRP were 2.05 times more likely to suffer from a MACE than those without HRP (hazards ratio: 2.05, 95% confidence interval: 1.04-4.02, P = .038); MACE risk was comparable between plaque rupture and plaque erosion. In conclusion, HRP was present in 24.8% of STEMI patients and associated with higher cardiovascular risk independent of plaque rupture, suggesting that HRP detected by OCT may help identify patients at high risk of future cardiac events.

Gut Metabolite Trimethylamine-N-Oxide in Atherosclerosis: From Mechanism to Therapy

Atherosclerosis is associated with various pathological manifestations, such as ischemic heart disease, ischemic stroke, and peripheral arterial disease, and remains a leading cause of public health concern. Atherosclerosis is an inflammatory disease characterized by endothelial dysfunction; vascular inflammation; and the deposition of lipids, cholesterol, calcium, and cellular debris within the vessel wall intima. In-depth studies of gut flora in recent years have shown that bacterial translocation and the existence of bacterial active products in blood circulation can affect the inflammatory state of the whole blood vessel. The gut flora is considered to be a large “secretory organ,” which produces trimethylamine-N-oxide (TMAO), short-chain fatty acids and secondary bile acids by breaking down the ingested food. Studies have shown that TMAO is an independent risk factor for the occurrence of malignant adverse cardiovascular events, but whether it is harmful or beneficial to patients with cardiovascular diseases with mild or no clinical manifestations remains controversial. We review the relationship between TMAO and its precursor (L-carnitine) and coronary atherosclerosis and summarize the potential molecular mechanism and therapeutic measures of TMAO on coronary atherosclerosis.

Plaque Erosion: A Distinctive Pathological Mechanism of Acute Coronary Syndrome

Plaque erosion (PE) is one of the most important pathological mechanisms underlying acute coronary syndrome (ACS). The incidence of PE is being increasingly recognized owing to the development and popularization of intracavitary imaging. Unlike traditional vulnerable plaques, eroded plaques have unique pathological characteristics. Moreover, recent studies have revealed that there are differences in the physiopathological mechanisms, biomarkers, and clinical outcomes between PE and plaque rupture (PR). Accurate diagnosis and treatment of eroded plaques require an understanding of the pathogenesis of PE. In this review, we summarize recent scientific discoveries of the pathological characteristics, mechanisms, biomarkers, clinical strategies, and prognosis in patients with PE.

Addition of Plasma Myeloperoxidase and Trimethylamine N-Oxide to the GRACE Score Improves Prediction of Near-Term Major Adverse Cardiovascular Events in Patients With ST-Segment Elevation Myocardial Infarction

Background: The Global Registry of Acute Coronary Events (GRACE) risk score (GRS) is an established powerful model in predicting prognosis of patients with acute coronary syndrome. However, it does not contain pathophysiological biomarkers. Myeloperoxidase (MPO) and trimethylamine N-oxide (TMAO) are novel biomarkers of different pathophysiological processes of acute myocardial infarction, and each of them predicts risk of adverse clinical outcomes. We aimed to investigate whether the addition of MPO and TMAO could improve a GRS-based prediction model in patients with ST-segment elevation myocardial infarction (STEMI).

Methods: A prospective cohort of 444 consecutive patients with STEMI who underwent primary percutaneous coronary intervention were enrolled in this study. Plasma levels of MPO and TMAO were measured using samples collected before the interventional procedure. GRS at admission was calculated. Death and nonfatal myocardial infarction were recorded as major adverse cardiac events (MACEs). Kaplan–Meier survival analysis with Cox proportional-hazards regression was used to identify predictive values of MPO and TMAO. Area under the receiver-operator characteristic curve (AUC) and net reclassification improvement (NRI) were calculated to evaluate the increment of predictive value for the combination of MPO and TMAO with GRS in predicting adverse clinical outcomes.

Results: During 6 months follow-up, 27 patients suffered MACEs. Both MPO (hazard ratio [HR]: 2.55, 95% confidence interval [CI]: 1.11–5.87; p < 0.05) and TMAO (HR: 4.50, 95% CI: 1.78–11.40, p < 0.01) predicted MACEs at 6 months. The AUC for MPO, TMAO, GRS, and their combination in predicting risk of MACEs at 6 months is 0.642, 0.692, 0.736, and 0.760, respectively. The addition of MPO and TMAO significantly improved the net reclassification of GRS for predicting MACEs at 6 months (NRI: 0.42, p = 0.032).

Conclusion: Plasma MPO and TMAO each predict near-term risk of adverse outcomes in patients with STEMI. Furthermore, the combination of MPO and TMAO with GRS enables more accurate prediction of cardiovascular events compared with GRS alone.

Residual SYNTAX Score in Relation to Coronary Culprit Plaque Characteristics and Cardiovascular Risk in ST Segment Elevation Myocardial Infarction: an Intravascular Optical Coherence Tomography Study

This study aimed to investigate the association of high-risk culprit plaque features by optical coherence tomography (OCT) with residual SYNTAX score (rSS) and the predictive value of rSS for major adverse cardiac events (MACE) in patients with ST segment elevation myocardial infarction (STEMI). We included 274 patients and divided them into 3 groups - rSS=0 (n=72), 0<rSS≤8 (n=134), and rSS>8 (n=68). There were significant differences in plaque characteristics among three groups (plaque rupture: 44.4% versus 59.0% versus 64.7%, lowest to highest rSS, p=0.040; OCT-defined high-risk plaques: 16.7% versus 23.9% versus 35.3%, lowest to highest rSS, p=0.036; calcification: 38.9% versus 52.5% versus 61.8%, lowest to highest rSS, p=0.024). During a mean follow-up of 2.2 years, MACE occurred in 47 (17.2%) patients; rSS >8 group had higher MACE risk compared to rSS=0 (HR: 2.68, 95%CI: 1.11-6.5, P=0.029). In conclusion, culprit plaque morphology was significantly correlated with rSS, and elevated rSS was associated with higher cardiovascular risk in STEMI patients. ClinicalTrials.gov : NCT03593928.

Plasma levels of trimethylamine-N-oxide can be increased with 'healthy' and 'unhealthy' diets and do not correlate with the extent of atherosclerosis but with plaque instability

AIMS

The microbiome-derived metabolite trimethylamine-N-oxide (TMAO) has attracted major interest and controversy both as a diagnostic biomarker and therapeutic target in atherothrombosis.

METHODS AND RESULTS

Plasma TMAO increased in mice on 'unhealthy' high-choline diets and notably also on 'healthy' high-fibre diets. Interestingly, TMAO was found to be generated by direct oxidation in the gut in addition to oxidation by hepatic flavin-monooxygenases. Unexpectedly, two well-accepted mouse models of atherosclerosis, ApoE-/- and Ldlr-/- mice, which reflect the development of stable atherosclerosis, showed no association of TMAO with the extent of atherosclerosis. This finding was validated in the Framingham Heart Study showing no correlation between plasma TMAO and coronary artery calcium score or carotid intima-media thickness (IMT), as measures of atherosclerosis in human subjects. However, in the tandem-stenosis mouse model, which reflects plaque instability as typically seen in patients, TMAO levels correlated with several characteristics of plaque instability, such as markers of inflammation, platelet activation, and intraplaque haemorrhage.

CONCLUSIONS

Dietary-induced changes in the microbiome, of both 'healthy' and 'unhealthy' diets, can cause an increase in the plasma level of TMAO. The gut itself is a site of significant oxidative production of TMAO. Most importantly, our findings reconcile contradictory data on TMAO. There was no direct association of plasma TMAO and the extent of atherosclerosis, both in mice and humans. However, using a mouse model of plaque instability we demonstrated an association of TMAO plasma levels with atherosclerotic plaque instability. The latter confirms TMAO as being a marker of cardiovascular risk.

Trimethylamine N-Oxide, a Gut Microbiota-Dependent Metabolite, is Associated with Frailty in Older Adults with Cardiovascular Disease

Objective

Our study aimed to explore the association between trimethylamine N-oxide and frailty in older adults with cardiovascular disease.

Patients and Methods

This cross-sectional study analyzed a total of 451 people aged 65 years or older who underwent comprehensive geriatric assessments. Frailty status was determined using a frailty index constructed with 48 variables according to the cumulative deficits model. Physical frailty and cognitive frailty were also assessed in detail. Fasting plasma TMAO was measured by mass spectrometry.

Results

The proportion of frail subjects was 29.9% (135/451). Plasma TMAO levels were significantly higher in frail patients than in nonfrail individuals (4.04 [2.84–7.01] vs 3.21 [2.13–5.03] µM; p<0.001). Elevated plasma TMAO levels were independently associated with the likelihood of frailty (OR 2.12, 95% CI 1.01–4.38, p=0.046). Dose–response analysis revealed a linear association between the TMAO concentration and the OR for frailty. A 2-unit increase in TMAO was independently correlated with physical frailty (OR 1.23, 95% CI 1.08–1.41, p for trend 0.002) and cognitive frailty (OR 1.21, 95% CI 1.01–1.45, p for trend 0.04).

Conclusion

Elevated circulating TMAO levels are independently associated with frailty among older adults with cardiovascular disease.