Two-sample Mendelian randomization to study the causal association between gut microbiota and atherosclerosis

Background

According to some recent observational studies, the gut microbiota influences atherosclerosis via the gut microbiota-artery axis. However, the causal role of the gut microbiota in atherosclerosis remains unclear. Therefore, we used a Mendelian randomization (MR) strategy to try to dissect this causative link.

Methods

The biggest known genome-wide association study (GWAS) (n = 13,266) from the MiBioGen collaboration was used to provide summary data on the gut microbiota for a two-sample MR research. Data on atherosclerosis were obtained from publicly available GWAS data from the FinnGen consortium, including cerebral atherosclerosis (104 cases and 218,688 controls), coronary atherosclerosis (23,363 cases and 187,840 controls), and peripheral atherosclerosis (6631 cases and 162,201 controls). The causal link between gut microbiota and atherosclerosis was investigated using inverse variance weighting, MR-Egger, weighted median, weighted mode, and simple mode approaches, among which inverse variance weighting was the main research method. Cochran's Q statistic was used to quantify the heterogeneity of instrumental variables (IVs), and the MR Egger intercept test was used to assess the pleiotropy of IVs.

Results

Inverse-variance-weighted (IVW) estimation showed that genus Ruminiclostridium 9 had a protective influence on cerebral atherosclerosis (OR = 0.10, 95% CI: 0.01-0.67, P = 0.018), while family Rikenellaceae (OR = 5.39, 95% CI: 1.50-19.37, P = 0.010), family Streptococcaceae (OR = 6.87, 95% CI: 1.60-29.49, P = 0.010), genus Paraprevotella (OR = 2.88, 95% CI: 1.18-7.05, P = 0.021), and genus Streptococcus (OR = 5.26, 95% CI: 1.28-21.61, P = 0.021) had pathogenic effects on cerebral atherosclerosis. For family Acidaminococcaceae (OR = 0.87, 95% CI: 0.76-0.99, P = 0.039), the genus Desulfovibrio (OR = 0.89, 95% CI: 0.80-1.00, P = 0.048), the genus RuminococcaceaeUCG010 (OR = 0.80, 95% CI: 0.69-0.94, P = 0.006), and the Firmicutes phyla (OR = 0.87, 95% CI: 0.77-0.98, P = 0.023) were protective against coronary atherosclerosis. However, the genus Catenibacterium (OR = 1.12, 95% CI: 1.00-1.24, P = 0.049) had a pathogenic effect on coronary atherosclerosis. Finally, class Actinobacteria (OR = 0.83, 95% CI: 0.69-0.99, P = 0.036), family Acidaminococcaceae (OR = 0.76, 95% CI: 0.61-0.94, P = 0.013), genus Coprococcus2 (OR = 0.76, 95% CI: 0.60-0.96, P = 0.022), and genus RuminococcaceaeUCG010 (OR = 0.65, 95% CI: 0.46-0.92, P = 0.013), these four microbiota have a protective effect on peripheral atherosclerosis. However, for the genus Lachnoclostridium (OR = 1.25, 95% CI: 1.01-1.56, P = 0.040) and the genus LachnospiraceaeUCG001 (OR = 1.22, 95% CI: 1.04-1.42, P = 0.016), there is a pathogenic role for peripheral atherosclerosis. No heterogeneity was found for instrumental variables, and no considerable horizontal pleiotropy was observed.

Conclusion

We discovered that the presence of probiotics and pathogens in the host is causally associated with atherosclerosis, and atherosclerosis at different sites is causally linked to specific gut microbiota. The specific gut microbiota associated with atherosclerosis identified by Mendelian randomization studies provides precise clinical targets for the treatment of atherosclerosis. In the future, we can further examine the gut microbiota's therapeutic potential for atherosclerosis if we have a better grasp of the causal relationship between it and atherosclerosis.

Assessment of the relationship between telomere length and atherosclerosis: A Mendelian randomization study

To evaluate the causal relationship between genetically determined telomere length (TL) and atherosclerosis (AS). We performed a 2-sample Mendelian randomization (MR) study to assess the potential causal relationship between TL and AS (coronary AS, cerebral AS, peripheral atherosclerosis (PAD), and AS, excluding cerebral, coronary, and PAD). The TL phenotype contained 472,174 participants, and the 4 subtypes of AS had 361,194, 218,792, 168,832, and 213,140 participants, all of European ancestries. The single nucleotide polymorphisms (SNPs) of TL strongly associated with the 4 atherosclerotic subtypes included in this study were 101, 92, 91, and 92, respectively. The odds ratios (ORs) and 95% confidence interval (CI) between TL and coronary AS calculated using inverse variance weighted (IVW) were 0.993 (0.988, 0.997), and the results were statistically significant (P < .05). The results between TL and cerebral AS, PAD, and AS (excluding cerebral, coronary, and PAD) were not statistically significant (P > .05). "Egger-intercept test" showed that there was no horizontal pleiotropy (P > .05); "leave-one-out analysis" sensitivity analysis showed that the results were stable and there were no instrumental variables with strong effects on the results; "MR- pleiotropy residual sum and outlier (PRESSO) test" showed 1 outlier for coronary AS and no outliers for the remaining subgroups. The results of the 2-sample MR analysis showed a causal association between TL and coronary AS but not with cerebral AS, PAD, and AS (excluding cerebral, coronary, and PAD). This may elucidate the observation that various vascular regions can be affected by AS but highlights the propensity of coronary arteries to be more susceptible to AS development.

Predictive Value of Noninvasive Peripheral Atherosclerosis Measurement for Coronary Artery Disease in Patients with Long T2DM Duration

Objective

This study aimed to compare the predictive value of carotid or femoral artery ultrasound for coronary artery disease (CAD) in type 2 Diabetes mellitus (T2DM) patients free from known CAD, and to assess the relationship with the severity of coronary artery stenosis.

Methods

Cross-sectional study in adults with a T2DM duration of at least 5 years and without established CAD. Carotid plaque score (CPS) and Gensini score were used to measure the severity of carotid and coronary artery stenosis, respectively, and patients were divided into no or mild group, moderate group, and severe group according to the tertile of the score. Univariate and multivariate logistic regression analysis was used to explore the possible risk factors for CAD. Receiver operating characteristic (ROC) curves were created to determine the most accurate assessment for detecting significant CAD (≥50% stenosis).

Results

245 patients (137 male) aged 68.21±9.5 years (range: 36-95 years), with T2DM duration 12.04± 6.17 years (range: 5-34 years), and without CVD were included. CAD was diagnosed in 165 patients (67.3%). Multiple regression analysis showed that CPS, femoral plaque, and smoking were independently and positively correlated with CAD. CPS yielded the highest area under the curve for detecting significant coronary disease (AUC=0.7323). In contrast, the area under the curve of femoral artery plaque and carotid intima-media thickness was lower than 0.7, which was at a lower prediction level.

Conclusion

In patients with long T2DM duration, CPS has a higher ability to predict the occurrence and severity of CAD. However, femoral artery plaque has special value in predicting moderate to severe coronary artery disease in patients with long-term T2DM.

Antithrombotic Treatment in Lower Extremity Peripheral Arterial Disease

Lower extremity arteries might be affected by atherosclerotic peripheral arterial disease (PAD), or by embolization causing ischaemic symptoms. Patients with PAD often have widespread atherosclerosis, and progression of PAD is associated with increased risk for both other cardiovascular events and cardiovascular mortality. Peripheral arterial disease patients should therefore be offered both non-pharmacological and pharmacological secondary prevention to reduce the risk for future ischemic arterial complications. This review is focussed on the rationale for recommendations on antiplatelet and anticoagulant treatment in PAD. Asymptomatic PAD does not warrant either anticoagulant or antiplatelet treatment, whereas patients with ischaemic lower extremity symptoms such as intermittent claudication or critical limb ischemia caused by atherosclerosis should be offered platelet antiaggregation with either low dose aspirin or clopidogrel. Combined treatment with aspirin and low-dose of the direct oral anticoagulant (DOAC) rivaroxaban should be considered and weighed against bleeding risk in symptomatic PAD patients considered at high risk for recurrent ischaemic events and in patients having undergone endovascular or open surgical intervention for PAD. Patiens with cardiogenic embolization to lower extremity arteries should be recommended anticoagulant treatment with either one of the DOACs (apixaban, dabigatran, edoxaban, and rivaroxaban) or warfarin.

Subclinical Measures of Peripheral Atherosclerosis and the Risk of New-Onset Atrial Fibrillation in the General Population: the Rotterdam Study

Background

Limited population‐based data on the (sex‐specific) link between subclinical measures of peripheral atherosclerosis and new‐onset atrial fibrillation (AF) exist.

Methods and Results

Subclinical measures of peripheral atherosclerosis including carotid intima‐media thickness (cIMT), carotid plaque, and ankle‐brachial index (ABI) were assessed at baseline and follow‐up examinations. A total of 12 840 participants free of AF at baseline from the population‐based Rotterdam Study were included. Cox proportional hazards models and joint models, adjusted for cardiovascular risk factors, were used to determine the associations between baseline and longitudinal measures of cIMT, carotid plaque, and ABI with new‐onset AF. During a median follow‐up of 9.2 years, 1360 incident AF cases occurred among 12 840 participants (mean age 65.2 years, 58.3% women). Higher baseline cIMT (fully‐adjusted hazard ratio [HR], 95% CI, 1.81, 1.21–2.71; P=0.0042), presence of carotid plaque (fully‐adjusted HR, 95% CI, 1.19, 1.04–1.35; P=0.0089), lower ABI (fully‐adjusted HR, 95% CI, 1.57, 1.14–2.18; P=0.0061) and longitudinal measures of higher cIMT (fully‐adjusted HR, 95% CI, 2.14, 1.38–3.29; P=0.0021), presence of carotid plaque (fully‐adjusted HR, 95% CI, 1.61, 1.12–2.43; P=0.0112), and lower ABI (fully‐adjusted HR, 95% CI, 4.43, 1.83–10.49; P=0.0007) showed significant associations with new‐onset AF in the general population. Sex‐stratified analyses showed that the associations for cIMT, carotid plaque, and ABI were mostly prominent among women.

Conclusions

Baseline and longitudinal subclinical measures of peripheral atherosclerosis (carotid atherosclerosis, and lower extremity peripheral atherosclerosis) were significantly associated with an increased risk of new‐onset AF, especially among women.

Registration

URL: https://www.trialregister.nl, https://www.apps.who.int/trialsearch/; Unique identifier: NL6645/NTR6831.

[Are hybrid technologies appropriate for revascularization of aortoiliac-femoral segment?]

OBJECTIVE

To compare various approaches to revascularization of aortoiliac-femoral segment.

MATERIAL AND METHODS

Data were collected prospectively for retrospective analysis. There were 192 patients with atherosclerotic lesion of the aortoiliac-femoral segment who underwent reconstructive surgeries. All patients were divided into 3 groups depending on the type of reconstruction: 85 patients underwent open surgical interventions, 63 patients - endovascular interventions, 44 patients - hybrid techniques. Between-group differences were considered significant at p-value <0.05.

RESULTS

Hybrid revascularization is characterized by less duration of surgery, blood loss and morbidity. Hybrid interventions ensured favorable primary patency compared to open surgery within the follow-up period.

CONCLUSION

Hybrid revascularization of aortoiliac-femoral segment is characterized by less duration of surgery, blood loss and morbidity.

Relationship Between Vascular Aging and Left Ventricular Concentric Geometry in Community-Dwelling Elderly: The Northern Shanghai Study

Purpose

There have been few recent studies regarding vascular aging and its relationship with left ventricular (LV) geometry. Moreover, the association of abnormal LV geometry with various kinds of vascular aging has not yet been systematically analyzed. Thus, this study aimed to further elucidate this relationship.

Materials and Methods

In this study, 3363 older participants (43.6% male, aged 71.1±5.9 years; 56.4% female, aged 71.1±6.1 years) derived from the Northern Shanghai Study were enrolled. Vascular aging criteria included arteriosclerosis, defined as carotid-femoral pulse wave velocity >10 m/s or brachial-ankle pulse wave velocity >1800 cm/s, and peripheral atherosclerosis, defined as ankle-brachial index <0.9, carotid artery intima-media thickness (cIMT) greater than 0.9 mm, or carotid plaque indicating carotid artery abnormality. Micro-albuminuria was defined as urinary albumin-to-creatinine ratio >30 mg/g. Decreased estimated glomerular filtration rate (eGFR) was defined as eGFR <60 mL/min/1.73 m².

Results

When vascular aging parameters were respectively adjusted for age and sex, arteriosclerosis, micro-albuminuria, and peripheral atherosclerosis were significantly associated with concentric remodeling, eccentric LV hypertrophy (LVH), and concentric LVH (P<0.045) but not with decreased eGFR or abnormal cIMT and presence of plaque. Peripheral atherosclerosis was strongly associated with LV concentric geometry (LVCG) when considering other covariates (risk factors, diseases, and treatments) (P<0.012).

Conclusion

Vascular aging parameters such as arteriosclerosis, micro-albuminuria, and peripheral atherosclerosis are significantly and independently associated with LVCG in community-dwelling older Chinese population, suggesting the importance of vascular aging during early clinical assessment of abnormal LV geometry change and serious cardiovascular events.

The novel role of IL-37 to enhance the anti-inflammatory response of regulatory T cells in patients with peripheral atherosclerosis

OBJECTIVES

Regulatory T cells (Tregs) mediate immunomodulation and protect against atherosclerosis. It is considered that reducing the amount of pro-inflammatory mediators could be achieved by enhancing the anti-inflammatory response, and this may be considered one of the main targets for therapy development. The inhibitory cytokines secreted by Tregs mainly include interleukin-10 (IL-10) and transforming growth factor-beta (TGF-β). Based on its known immunosuppressive involvement with other inflammatory disorders, we hypothesized that the newly characterized cytokine interleukin-37 (IL-37) might be associated with the inhibitory functions of Treg in atherosclerosis. Immune regulatory functions of IL-37 have not been completely clarified. Accordingly, we speculated that IL-37 might play a regulatory role in the immunosuppression of Tregs in atherosclerotic disease.

METHODS

Real-time polymerase chain reaction and enzyme linked immunosorbent assay were used to test gene expression and protein levels of IL-37 in peripheral blood and localized freshly resected arterial tissues from 84 patients with peripheral arterial occlusive disease and 50 non-atherosclerotic subjects. Results were correlated to disease hallmarks. We also evaluated the ability of recombinant IL-37 to modulate Treg cytokine secretion and T cell inhibition in relation to atherosclerotic disorder in vitro.Results: Our results revealed that IL-37 was increased in patients with chronic lower limb atherosclerotic ischemia, compared to non-atherosclerotic controls. In addition, the expression levels of circulating IL-37 correlated with disease severity of chronic lower limb ischemia. Supplementation with rIL-37 augmented levels of released IL-10 and TGF-β in supernatants of T cells co-cultured with Tregs in the enrolled patients.Conclusions: Results suggest a role for IL-37 in mediating anti-inflammatory functions in the atherosclerotic process, potentially involving enhancement of Treg inhibitory function and anti-inflammatory cytokine secretion with a particularly marked direct response in severe disease.

Changes and significance of T helper-9 cells and interleukin-9 in patients with atherosclerotic chronic lower limb ischemia: Effect on IL-17 release

OBJECTIVES

Atherosclerosis is considered as a chronic inflammatory disorder where the central role of T cells in its pathogenesis is well known. T helper-9 cells have a distinctive effect upon the inflammatory processes. They stimulate macrophages via secretion of their cytokine interleukin-9. Based on its known involvement with other inflammatory disorders, we hypothesized that interleukin-9 might be associated with the inflammatory limb of peripheral atherosclerotic disease.

METHODS

We tested this hypothesis on peripheral blood mononuclear cells (PBMCs) and freshly resected arterial tissues from 84 patients with peripheral arterial occlusive disease (PAOD) and 50 non-atherosclerotic subjects. A number of experimental methods were used including flow cytometry analysis of T helper-9 cells using anti-CD3, anti-CD4, and anti-interleukin-9monoclonal antibodies as well as real-time polymerase chain reaction for the assessment of gene expression of interleukin-9. In addition, circulating serum levels of interleukin-9 were measured using enzyme linked immunosorbent assay. We also evaluated the ability of recombinant interleukin-9 to modulate IL-17 release in cultured isolated CD3+ T cells with relation to atherosclerotic disorder in vitro.

RESULTS AND CONCLUSIONS

Here we report increased percentages of T helper-9 cells and interleukin-9 levels in patients with chronic lower limb atherosclerotic ischemia, compared to healthy controls. Through investigation of different atherosclerotic patient populations with different disease stages, we found elevated interleukin-9 level both systemically and within the lesion and increased expression of cells in severe disease stages. The current study also revealed enhanced expression of mRNA levels of interleukin-9 within the atherosclerotic lesion when compared with non-atherosclerotic vessels. Levels of released IL-17 in CD3+ T cell culture supernatants supplemented with interleukin-9 were significantly positively correlated in the enrolled patients. The results suggest a role for T helper-9 cells and IL-9 in atherosclerotic process, potentially involving IL-17-mediated mechanisms. Indeed, we found that interleukin-9 promoted IL-17 release in PBMCs, with a particularly marked response in severe disease.

[Do the patients with peripheral atherosclerosis need to a medical therapy before the revascularization?]

In the review article are provided the approaches to the therapy for improvement of prognosis in patients with peripheral and multifocal atherosclerosis which are available now; some limitations and a real situation are designated for the antithrombotic therapy in this category of patients. According to the clinical trial COMPASS the prospects of wide use of a combination of acetylsalicylic acid and a rivaroxsaban of 2.5 mg 2 times a day in the patients with chronic coronary heart disease and/or symptom peripheral atherosclerosis are designated.

[Therapeutic aspects of the choice of antithrombotic therapy in patients with multifocal lesions of peripheral arteries]

The article discusses the features of the development and course of the atherosclerotic process in various vascular basins. Variability of factors such as local hemodynamics, differences in the structure of the arteries can influence the formation of atherosclerotic plaque and the progression of the atherosclerotic process. A better understanding of the nature and causes of these differences can help improve the tactics of treatment and prevention of vascular complications. Analysis of the results of the COMPASS study (cardiovascular outomes for people using anticoagulation stategies - evaluation of cardiovascular outcomes in patients receiving anticoagulant therapy) showed for the first time the effectiveness of combination therapy using rivaroxaban direct anticoagulant at a dose of 2.5 mg 2 times a day in combination with acetylsalicylic acid at a dose of 100 mg per day. It was shown that, against the background of combination therapy, patients with coronary heart disease or atherosclerotic peripheral artery disease showed a significant decrease in the incidence of events of the primary end point of efficacy: a reduced risk of stroke, cardiovascular mortality and myocardial infarction, and also a reduction in the risk of major lower amputations extremities and total mortality in patients with stable forms of atherosclerosis. The emergence of combination therapy can help to achieve both an improvement in the overall prognosis and the prognosis of limb preservation in patients with multifocal arterial lesion.

[Choice of the revascularization method for patients of elderly age with infraeinguvinal arterial disease.]

The aim of the study was to perform a comparative evaluation of the use of various methods of reconstructive assistance in the defeat of the femoral-tibial segment in elderly patients with peripheral arterial disease. 253 patients over 60 years old (60-74 years and more than 75 years) with atherosclerotic lesions of arteries below the inguinal ligament were examined and revascularized. According to the type of reconstruction performed, the patients were divided into 3 groups: 98 patients underwent open surgical interventions; 116 patients underwent endovascular interventions; 39 people performed hybrid reconstructions. The shorter duration of each stage of hybrid interventions, minor blood loss, and stability of hemodynamics during the perioperative period positively characterize hybrid effects. It was found that there was a shorter stay in the intensive care unit and shorter hospitalization of patients after hybrid revascularization methods compared to open methods. The absence of dangerous complications and the primary patency of the operated segment in the early postoperative period, approaching 100%, characterize hybrid techniques as an effective method of treating patients with infraganginal arterial disease. Conclusion: Hybrid reconstructions are promising in elderly patients who have severe comorbidity due to less operational blood loss, shorter duration of intervention and the minimum number of postoperative complications.

Intestinal fatty acid binding protein Ala54Thr polymorphism is associated with peripheral atherosclerosis combined with type 2 diabetes mellitus

BACKGROUND

Intestinal fatty acid-binding protein 2 (FABP2) is expressed in enterocytes and binds saturated and unsaturated long-chain fatty acids. The FABP2 Ala54Thr polymorphism has been reported to effect lipid metabolism. The aim of the present study was to assess the relationship between this polymorphism and peripheral atherosclerosis combined with type 2 diabetes mellitus (T2DM) in an Egyptian population.

METHODS

The study was performed on 100 T2DM patients with peripheral atherosclerosis and 100 control subjects. The Ala54Thr polymorphism was analyzed by polymerase chain reaction-restriction fragment length polymorphism, whereas serum FABP2 levels were determined using ELISA. Fasting blood glucose, fasting serum insulin concentrations, HbA1c, lipid profile, body mass index (BMI) and systolic and diastolic blood pressure (SBP and DBP, respectively) were determined.

RESULTS

There was a higher frequency of the Thr54 allele among the patient group (P = 0.002). In Ala54/Thr54 heterozygotes and carriers of the rare Thr54/Thr54 genotype, there were significant increases in BMI and FABP2. Those with the Thr54/Thr54 genotype had significantly decreased high-density lipoprotein cholesterol (HDL-C) concentrations; in addition, those with the Thr54/Thr54 genotype had significantly higher SBP and DBP than subjects with the Ala54/Ala54 and Ala54/Thr54 genotypes. There was a positive correlation between FABP2 levels and BMI, SBP and DBP, and a negative correlation with HDL-C.

CONCLUSIONS

The Thr54 allele of the FABP2 Ala54Thr polymorphism was associated with an increased incidence of peripheral atherosclerosis combined with T2DM in the population studied.

Clinically relevant depressive symptoms and peripheral arterial disease in elderly men and women. Results from a large cohort study in Southern China

OBJECTIVE

Results from previous epidemiological studies on the relationship between depression and peripheral arterial diseases (PADs) were mixed. Therefore, a study was conducted to investigate this relationship in a large Chinese elderly sample.

METHODS

Cross-sectional data from the baseline examination of a large cohort study on Chinese elderly were used in this current study. A stratified convenience sample of 3985 Hong Kong men and women aged 65 to 92 were recruited from the community. Clinically relevant depressive symptoms were assessed by the use of a validated screening instrument for depression: the Chinese version of the Short Form of Geriatric Depression Scale. PAD was assessed by the ankle-brachial index, with an index of <0.9 indicating the presence of PAD. Multiple logistic regression was used to compare the presence of PAD in depressed and nondepressed subjects, controlling for confounding variables for the relationship.

RESULTS

In the total subject population, more severe peripheral atherosclerosis was associated with a higher prevalence of depressive disorders. The presence of peripheral atherosclerosis was associated with an adjusted odds ratio of 1.46 (95% confidence interval=1.01-2.10) of having clinically relevant depressive symptoms.

CONCLUSION

We showed that depressive symptoms were associated with peripheral atherosclerosis in the Asian elderly after adjusting for stroke and cardiovascular diseases. Prospective studies are needed to provide conclusive evidence on the causality of the relationship between peripheral atherosclerosis and depressive symptoms.