Mendelian randomization for cardiovascular diseases: principles and applications

Insulin-related traits and prostate cancer: A Mendelian randomization study

Investigating the causal relationship between insulin secretion and prostate cancer (PCa) development is challenging due to the multifactorial nature of PCa, which complicates the isolation of the specific impact of insulin-related factors. We conducted a Mendelian randomization (MR) study to investigate the associations between insulin secretion-related traits and PCa. We used 36, 60, 56, 23, 48, and 49 single nucleotide polymorphisms (SNPs) as instrumental variables for fasting insulin, insulin sensitivity, proinsulin, and proinsulin in nondiabetic individuals, individuals with diabetes, and individuals receiving exogenous insulin, respectively. These SNPs were selected from various genome-wide association studies. To clarify the causal relationship between insulin-related traits and PCa, we utilized a multivariable MR analysis to adjust for obesity and body fat percentage. Additionally, two-step Mendelian randomization was conducted to assess the role of insulin-like growth factor 1 (IGF-1) in the relationship between proinsulin and PCa. Two-sample MR analysis revealed strong associations between genetically predicted fasting insulin, insulin sensitivity, proinsulin, and proinsulin in nondiabetic individuals and the development of PCa. After adjustment for obesity and body fat percentage using multivariable MR analysis, proinsulin remained significantly associated with PCa, whereas other factors were not. Furthermore, two-step MR analysis demonstrated that proinsulin acts as a negative factor in prostate carcinogenesis, largely independent of IGF-1. This study provides evidence suggesting that proinsulin may act as a negative factor contributing to the development of PCa. Novel therapies targeting proinsulin may have potential benefits for PCa patients, potentially reducing the need for unnecessary surgical treatments.

Causal role of circulating inflammatory cytokines in cardiac diseases, structure and function

BACKGROUND

Inflammation is implicated in cardiovascular disease (CVD) pathogenesis, but causal roles of specific circulating inflammatory cytokines remain unclear. Mendelian randomization (MR) studies are well-poised to provide etiological insights beyond constraints of conventional research.

METHODS

We conducted a large-scale MR study to investigate potential causal relationships of 91 inflammatory proteins with CVD outcomes and cardiac remodeling using summary-level genetic data. Outcomes included coronary artery disease, myocardial infarction, stroke, atrial fibrillation, heart failure, abdominal aortic aneurysm, deep vein thrombosis of lower extremities, pulmonary embolism, cardiac structure and functional parameters. Inverse-variance weighted analysis was undertaken as the primary analysis, with several sensitivity analyses applied.

RESULTS

Hepatocyte growth factor (HGF) demonstrated a causal relationship with increased susceptibility to both any stroke (OR 1.111; 95 % CI 1.044 - 1.183; P = 9.50e-04) and ischemic stroke (OR 1.121; 95 % CI 1.047 - 1.200; P = 1.04e-03). Programmed cell death 1 ligand 1 (PD-L1) was negatively associated with atrial fibrillation risk (OR 0.936, 95 % CI 0.901 - 0.973; P = 7.69e-04). CCL20, CDCP1, Flt3L and IL-10RA were identified as causal coronary artery disease risk factors, while LIF and ST1A1 had protective effects. IL-4 and LIF-R demonstrated causal links with right heart functional changes.

CONCLUSIONS

Our MR study nominates specific circulating inflammatory cytokines as potential targets for CVD treatment and prevention. Further research into mechanisms and clinical translation are warranted.

Unveiling the causal relationship between circulating levels of micronutrients and risk of facial aging: A Mendelian randomization study

Facial aging involves a continuous sequence of complex, interrelated events that impact numerous facial tissues. The aim of the study was to elucidate the casual relationship between circulating micronutrients and risk of facial aging. A two-sample Mendelian randomization analysis was performed using genetic data from genome-wide association studies. The inverse-variance weighted method is used for causal effect estimation, and additional tools such as Mendelian randomization-Egger, weighted median, simple mode, and weighted mode were used to refine the analysis. We conducted an in-depth examination of the correlation between several micronutrient blood levels and the risk of facial aging, and identified 3 key micronutrients (selenium, carotene, and iron) that may have a significant impact on skin health. Inverse-variance weighted results indicate that selenium levels were positively correlated with the risk of facial aging (odds ratio [OR] 1.005, P = .027), while a negative causal effect of carotene (OR 0.979, P = .024) and iron (OR 0.976, P = .009) on age-related facial alterations was observed. This study offers a new and insightful perspective on the current understanding of antiaging strategies, particularly the importance of appropriate consumption of essential micronutrients to maintain healthy skin condition.

Aortic mineralization triggers the risk of acute type B aortic dissection

BACKGROUND AND AIMS

The role of aortic mineralization in the pathogenesis of acute type B aortic dissection (TBAD) is unclear. Whether thoracic aortic calcification (TAC) and circulating alkaline phosphatase (ALP) activity are associated with acute TBAD risk remains elusive.

METHODS

Observational and Mendelian randomization (MR) studies were conducted sequentially. Using propensity score matching (1:1) by age and sex, patients with acute TBAD (n = 125) were compared with control patients (n = 125). Qualitative (score) and quantitative (volume) analyses of the TAC burden on different thoracic aortic segments were conducted using non-enhanced computed tomography. Univariate and multivariate analyses were used to identify significant independent risk factors for TBAD and TAC burden, respectively. MR was finally used to determine the causal relationship between elevated ALP activity and TBAD risk.

RESULTS

The qualitative and quantitative analyses revealed that TAC burden was significantly higher in the TBAD group, except for in the ascending aortic segment (both p < 0.05). Preoperative circulating ALP was significantly elevated in the TBAD group (p < 0.001). The elevated TAC burden score on the descending thoracic aortic segment (odds ratio [OR] 3.31, 95% confidence interval [CI] 1.31-8.37) and increased ALP activity (OR 1.03, 95% CI 1.01-1.06) was independently associated with TBAD risk. Interestingly, ALP was significantly positively associated with TAC burden, and MR analyses confirmed that ALP genetically predicted TBAD risk.

CONCLUSIONS

Elevated ALP may trigger TBAD risk via the increased volume of TAC. Aortic mineralization may not protect the aorta itself.

The function and therapeutic potential of transfer RNA-derived small RNAs in cardiovascular diseases: A review

Transfer RNA-derived small RNAs (tsRNAs) are a class of small non-coding RNA (sncRNA) molecules derived from tRNA, including tRNA derived fragments (tRFs) and tRNA halfs (tiRNAs). tsRNAs can affect cell functions by participating in gene expression regulation, translation regulation, intercellular signal transduction, and immune response. They have been shown to play an important role in various human diseases, including cardiovascular diseases (CVDs). Targeted regulation of tsRNAs expression can affect the progression of CVDs. The tsRNAs induced by pathological conditions can be detected when released into the extracellular, giving them enormous potential as disease biomarkers. Here, we review the biogenesis, degradation process and related functional mechanisms of tsRNAs, and discuss the research progress and application prospects of tsRNAs in different CVDs, to provide a new perspective on the treatment of CVDs.

Epilepsy and childhood psychiatric disorders: a two-sample bidirectional Mendelian randomization study

BACKGROUND

Observational studies have indicated that psychiatric disorders are the most common comorbidities in pediatric epilepsy. However, the existence and direction of a causal relationship between the two remains controversial. This study aims to investigate the association between common childhood psychiatric disorders and epilepsy using a two-sample, bidirectional Mendelian randomization (MR) approach.

METHODS

Genetic instruments were obtained from the most recent and largest genome-wide association studies (GWAS), including datasets for epilepsy (N_case = 29,994, N_control = 52,538), attention deficit hyperactivity disorder (ADHD) (N_case = 38,691, N_control = 186,843), autism spectrum disorder (ASD) (N_case = 18,381, N_control = 27,969), and Tourette syndrome (TS) (N_case = 4,819, N_control = 9488). MR analyses were conducted using the inverse variance weighted (IVW) method, weighted median method, and MR-Egger regression.

RESULTS

No reliable evidence was found to suggest a causal effect of ADHD, ASD, or TS on epilepsy, nor was there any reliable evidence indicating that epilepsy increases the risk of these three psychiatric disorders. These findings remained consistent across various sensitivity analyses.

CONCLUSION

Although observational studies have highlighted a high comorbidity rate between pediatric epilepsy and psychiatric disorders like ADHD and ASD, the MR analysis did not confirm a causal relationship between them. This suggests that previous studies might have been influenced by confounding biases or other biases, potentially overestimating the true relationship. A deeper understanding of the mechanisms underlying these comorbidities is crucial for refining the treatment of pediatric epilepsy.

Proprotein convertase subtilisin/kexin type 9 as a drug target for abdominal aortic aneurysm

PURPOSE OF REVIEW

There are no current drug therapies to limit abdominal aortic aneurysm (AAA) growth. This review summarizes evidence suggesting that inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9) may be a drug target to limit AAA growth.

RECENT FINDINGS

Mendelian randomization studies suggest that raised LDL and non-HDL-cholesterol are causal in AAA formation. PCSK9 was reported to be upregulated in human AAA samples compared to aortic samples from organ donors. PCSK9 gain of function viral vectors promoted aortic expansion in C57BL/6 mice infused with angiotensin II. The effect of altering PCSK9 expression in the aortic perfusion elastase model was reported to be inconsistent. Mutations in the gene encoding PCSK9, which increase serum cholesterol, were associated with increased risk of human AAA. Patients with AAA also have a high risk of cardiovascular death, myocardial infarction and stroke. Recent research suggests that PCSK9 inhibition would substantially reduce the risk of these events.

SUMMARY

Past research suggests that drugs that inhibit PCSK9 have potential as a novel therapy for AAA to both limit aneurysm growth and reduce risk of cardiovascular events. A large multinational randomized controlled trial is needed to test if PCSK9 inhibition limits AAA growth and cardiovascular events.

Crosstalk between gastrointestinal tract disorders and obstructive sleep apnea

PURPOSE

Clinical studies suggested associations between obstructive sleep apnea (OSA) and gastrointestinal tract disorders. This study aims to investigate the genetic causal relationship between OSA and gastrointestinal tract disorders, specifically gastroesophageal reflux disease (GERD) and inflammatory bowel disease (IBD).

METHODS

In this study, we employed two-sample Mendelian Randomization (MR) analysis to investigate the potential relationships between OSA and GERD, and between OSA and IBD. More specifically, the primary analysis utilized inverse variance weighting (IVW). Weighted median, MR Egger, and MR PRESSO were applied to complicate potential violations of MR assumptions. Also, sensitivity analysis was evaluated and similar analysis was performed again after outliers were removed. Additionally, multivariable MR (MVMR) was conducted for associated pairs to adjust for obesity.

RESULTS

Genetically predicted risk of GERD increased OSA risk by approximately 60% (ORIVW = 1.62, 95%CI = [1.43,1.84]) which was also stable by other complicated approaches, and even with BMI adjusted by MVMR (ORadjBMI[95%CI] = 1.26 [1.15,1.37]). Besides, OSA showed a mild causal effect on increased GERD risk after adjusting for obesity (ORadjBMI[95%CI] = 1.05 [1.02,1.08]). Additionally, OSA increased the risks for IBD (ORIVW[95%CI] = 1.36 [1.12,1.65]), including a higher risk of CD (ORIVW[95%CI] = 1.41 [1.08,1.83]), and a trend for increasing UC risk (ORIVW[95%CI] = 1.29 [0.99,1.67]).

CONCLUSION

GERD exerts a substantial causality on increasing the risk of OSA. Conversely, the potential for a causal relationship that OSA contributes to the development of GERD or IBD remains probable. These findings support the crosstalk between gastrointestinal tract disorders and OSA.

The Causal Association Between Obstructive Sleep Apnea and Child-Onset Asthma Come to Light: A Mendelian Randomization Study

Purpose

Obstructive sleep apnea (OSA) had been associated with asthma in observational studies, but the effect of OSA on the onset of asthma in childhood or adulthood remains unclear, and the causal inferences have not been confirmed. This study aims to investigate the potential causal association between OSA with asthma, including different age-of-onset subtypes, providing reliable basis for the clinical treatment of OSA and asthma.

Patients and Methods

Causality between OSA and asthma was assessed using a two-sample bi-directional Mendelian randomization (MR) analysis. OSA data were obtained from the FinnGen consortium R9, while asthma and its subtypes (adult-onset asthma, child-onset asthma, and moderate-to-severe asthma) were sourced from the IEU OpenGWAS project. The inverse-variance weighted (IVW) method was chosen as the primary analysis and was complemented by various sensitivity analyses. The MR-PRESSO outlier test was employed to systematically identify and remove outlier variants, mitigating heterogeneity and potential effects of horizontal pleiotropy.

Results

The MR analyses provided evidence of genetically predicted OSA having a promoting effect on child-onset asthma (OR,1.49; 95% CI, 1.05-2.11; P=0.025) and moderate-to-severe asthma (OR,1.03; 95% CI, 1.00-1.06; P=0.046). However, no causal association between OSA with asthma and adult-onset asthma was observed.

Conclusion

Our study revealed a causal association between OSA and child asthma, but not in adults. Moderate-to-severe asthma may have a potential promoting effect on OSA. These findings underscore the importance of age-specific considerations in managing asthma and suggests the need for personalized approaches in clinical practice.

Causal association between telomere length and female reproductive endocrine diseases: a univariable and multivariable Mendelian randomization analysis

BACKGROUND

The relationship between leukocyte telomere length (LTL) and female reproductive endocrine diseases has gained significant attention and research interest in recent years. However, there is still limited understanding of the exact impacts of LTL on these diseases. Therefore, the primary objective of this study was to investigate the genetic causal association between LTL and female reproductive endocrine diseases by employing Mendelian randomization (MR) analysis.

METHODS

Instruments for assessing genetic variation associated with exposure and outcome were derived from summary data of published genome-wide association studies (GWAS). Inverse-variance weighted (IVW) was utilized as the main analysis method to investigate the causal relationship between LTL and female reproductive endocrine diseases. The exposure data were obtained from the UK Biobanks GWAS dataset, comprising 472,174 participants of European ancestry. The outcome data were acquired from the FinnGen consortium, including abnormal uterine bleeding (menorrhagia and oligomenorrhea), endometriosis (ovarian endometrioma and adenomyosis), infertility, polycystic ovary syndrome (PCOS), premature ovarian insufficiency (POI) and premenstrual syndrome (PMS). Furthermore, to account for potential confounding factors such as smoking, alcohol consumption, insomnia, body mass index (BMI) and a history of pelvic inflammatory disease (PID), multivariable MR (MVMR) analysis was also conducted. Lastly, a series of pleiotropy tests and sensitivity analyses were performed to ensure the reliability and robustness of our findings. P < 0.0063 was considered to indicate statistically significant causality following Bonferroni correction.

RESULTS

Our univariable MR analysis demonstrated that longer LTL was causally associated with an increased risk of menorrhagia (IVW: odds ratio [OR]: 1.1803; 95% confidence interval [CI]: 1.0880-1.2804; P = 0.0001) and ovarian endometrioma (IVW: OR: 1.2946; 95%CI: 1.0970-1.5278; P = 0.0022) at the Bonferroni significance level. However, no significant correlation was observed between LTL and oligomenorrhea (IVW: OR: 1.0124; 95%CI: 0.7350-1.3946; P = 0.9398), adenomyosis (IVW: OR: 1.1978; 95%CI: 0.9983-1.4372; P = 0.0522), infertility (IVW: OR: 1.0735; 95%CI: 0.9671-1.1915; P = 0.1828), PCOS (IVW: OR: 1.0633; 95%CI: 0.7919-1.4278; P = 0.6829), POI (IVW: OR: 0.8971; 95%CI: 0.5644-1.4257; P = 0.6459) or PMS (IVW: OR: 0.7749; 95%CI: 0.4137-1.4513; P = 0.4256). Reverse MR analysis indicated that female reproductive endocrine diseases have no causal effect on LTL. MVMR analysis suggested that the causal effect of LTL on menorrhagia and ovarian endometrioma remained significant after accounting for smoking, alcohol consumption, insomnia, BMI and a history of PID. Pleiotropic and sensitivity analyses also showed robustness of our results.

CONCLUSION

The results of our bidirectional two-sample MR analysis revealed that genetically predicted longer LTL significantly increased the risk of menorrhagia and ovarian endometrioma, which is consistent with the findings from MVMR studies. However, we did not notice any significant effects of LTL on oligomenorrhea, adenomyosis, infertility, PCOS, POI or PMS. Additionally, reproductive endocrine disorders were found to have no impact on LTL. To enhance our understanding of the effect and underlying mechanism of LTL on female reproductive endocrine diseases, further large-scale studies are warranted in the future.

The role of Immune cells in Alzheimer's disease: a bidirectional Mendelian randomization study

Background

Alzheimer's disease (AD) is a leading cause of dementia, characterized by the accumulation of amyloid-beta (Aβ) and hyperphosphorylated tau proteins, leading to neuroinflammation and neuronal damage. The role of the immune system in AD pathogenesis is increasingly recognized, prompting an exploration of the causal relationship between immune cells and AD by using Mendelian randomization (MR) approaches.

Methods

Utilizing genome-wide association study (GWAS) data from European cohorts, we conducted an MR study to investigate the causal links between immune cell phenotypes and AD. We selected single nucleotide polymorphisms (SNPs) associated with immune cell traits at a genome-wide significance threshold and applied various MR methods, including MR Egger, Weighted median, and inverse variance weighted analysis, to assess the causality between 731 immune phenotypes and AD.

Results

Our MR analysis identified 15 immune cell types with significant causal relationships to AD pathogenesis. Notably, the absolute count of CD28-CD4-CD8- T cells and the expression of HLA DR on B cells were linked to a protective effect against AD, while 13 other immune phenotypes were identified as contributing to the risk factors for the disease. The causal effects of AD on immunophenotypic traits are predominantly negative, implying that AD may impair the functionality of immune cells. Validation through independent datasets, such as FinnGen and GCST90027158, confirmed the causal association between six specific immune cells and AD.

Conclusion

This comprehensive MR study elucidates the intricate network of causal relationships between diverse immunophenotypic traits and AD, providing novel insights into the immunopathogenesis of AD. The findings suggest potential immunological targets that could be leveraged for early diagnosis, disease monitoring, and therapeutic intervention.

The causal relationship between gut microbiota and alopecia areata: a Mendelian randomization analysis

Background

Increasing evidence suggests a robust correlation between the gut microbiome and alopecia areata. In light of the extensive diversity of gut microbiota, this study aims to utilize state-of-the-art and comprehensive data to explore the causative association between gut microbiota and alopecia areata.

Objective

We conducted a Mendelian randomization (MR)-based two-sample study to elucidate the causal relationship between gut microbiota and alopecia areata.

Method

Summary information on Ncase = 767 and Ncontrol = 394,105 cases of alopecia areata was obtained from the FinnGen study. A total of 473 gut microbial taxa were summarized from the genome-wide association study (GWAS) catalog. The study comprised a forward Mendelian randomization (MR) analysis with the gut microbiome as the exposure factor and alopecia areata as the outcome, as well as a reverse MR analysis with alopecia areata as the exposure factor and the gut microbiome as the outcome. Various analytical methods including inverse variance weighting (IVW), Weighted Median, MR-Egger, Weighted Mode, and Simple Mode were employed. Subsequently, sensitivity analysis was conducted to ensure the robustness of our research findings.

Result

This study has established a causal relationship between gut microbiota and alopecia areata. Forward causal analysis revealed causality relationships between 16 gut microbial taxa and alopecia areata, while reverse causal analysis found that there may be a causal relationship between alopecia areata and 16 gut microbial taxa (not statistically significant).

Conclusion

Our study findings suggest a causal relationship between gut microbiota and alopecia areata, providing potential guidance for future clinical trials.

Causal Effects and Immune Cell Mediators of Prescription Analgesic Use and Risk of Liver Cancer and Precancerosis in European Population: A Mendelian Randomization Study

Diverse clinical observations and basic studies have been conducted to explore the implications of analgesic medications in liver diseases. However, the direct causal relationship between prescription analgesic use (PAU) and the risk of liver cancer and precancerosis remains unclear. Thus, we aimed to reveal the conceivable causal effect of PAU on liver cancer and precancerosis, with immune cells as mediating factors. Two-sample Mendelian randomization (MR) analyses were performed to ascertain the causality of PAU on liver cancer and precancerosis. Sensitivity analysis approaches were employed to assess the heterogeneity and pleiotropy of results. Our findings revealed a causal correlation between different PAUs and the risk of liver cancer and alcoholic liver disease (ALD). Specifically, salicylic acid derivatives (SADs) and anilide medications were found to have a protective effect on liver cancer. And non-steroidal anti-inflammatory drugs (NSAIDs) and anilide medications showed a causal impact on ALD. Finally, mediation analyses found that anilide medications influence liver cancer through different immune cell phenotypes. Our research provides new genetic evidence for the causal impact of PAU on liver cancer and precancerosis, with the mediating role of immune cells demonstrated, offering a valuable foundation for researching analgesic medications in liver cancer and precancerosis treatment.

Anorexia and bulimia in relation to ulcerative colitis: a Mendelian randomization study

Background

Evidence for anorexia and bulimia in relation to the risk of ulcerative colitis (UC) is limited and inconsistent. The objective of this research was to utilize bi-directional, two-sample Mendelian randomization (MR) analysis to predict the causal association between anorexia nervosa and bulimia nervosa with UC.

Methods

The genome-wide association studies (GWAS) provided data for anorexia and bulimia from the UK Biobank, utilizing single-nucleotide polymorphisms (SNP) as instrumental variables. Additionally, genetic associations with UC were collected from various sources including the FinnGen Biobank, the UK Biobank and the International Inflammatory Bowel Disease Genetics Consortium (IIBDGC). The main analytical approach utilized in this study was the inverse-variance-weighted (IVW) method. To evaluate horizontal pleiotropy, the researchers conducted MR-Egger regression and MR-PRESSO global test analyses. Additionally, heterogeneity was assessed using the Cochran's Q test.

Results

This study found a negative association between genetically predicted bulimia (OR = 0.943, 95% CI: 0.893-0.996; p = 0.034) and the risk of UC in the IIBDGC dataset, indicating that individuals with bulimia have approximately a 5.7% lower risk of developing UC. No association was observed in the other two datasets. Conversely, genetically predicted anorexia was not found to be causally associated with UC. In bi-directional Mendelian randomization, UC from the IIBDGC dataset was negatively associated with the risk of anorexia (OR = 0.877, 95% CI: 0.797-0.965; p = 0.007), suggesting that UC patients have approximately a 12.3% lower risk of developing anorexia, but not causally associated with bulimia.

Conclusion

Genetically predicted bulimia may have a negative association with the onset of UC, while genetically predicted anorexia does not show a causal relationship with the development of UC. Conversely, genetically predicted UC may have a negative association with the development of anorexia.

The Association Between Smoking Behavior and the Risk of Hypertension: Review of the Observational and Genetic Evidence

Background

Cigarette smoking is one of the world's largest avoidable risk factors for morbidity and mortality. Numerous studies have investigated the association between smoking and hypertension (HTN). Although observational data and cross-sectional research often exhibit a link between smoking and HTN, establishing causation remains challenging owing to potential confounding variables. Mendelian randomization (MR), a genetic epidemiological technique that employs genetic variants as instrumental variables, offers a more robust approach for evaluating causal links. This review aimed to explore both the observational and causal relationships between smoking and the risk of HTN.

Methodology

A comprehensive literature search across major electronic databases was conducted to identify relevant observational and Mendelian randomization (MR) studies on smoking and HTN risk. Various characteristics were included during study selection, such as study design, exposure assessment, and age range. Standardized processes were used for data retrieval and quality evaluation.

Results

Analysis of observational data revealed a paradoxical association between smoking and the risk of HTN, where a lower risk was observed among current smokers when compared to non-smokers. However, observational analysis also presented a dose-response effect with greater smoking intensity showed a modest linear increase in HTN risk, and older smoking initiation was associated with a slight increase in HTN risk (compared with younger). In contrast, MR-based causal estimates provide inconsistent evidence regarding the causal relationship between smoking behavior and HTN. Some MR analyses indicated a potential causal link between smoking and HTN; but this was not consistent.

Conclusion

Observational studies suggest a paradoxical association between smoking and HTN. However, MR studies do not provide sufficient evidence to establish a causal relationship. Regardless, lifestyle variables remain crucial for overall health. Healthcare professionals should regularly assess smoking status and provide counseling for quitting. Further research is needed to clarify the underlying processes, identify mediators, and evaluate the interventions.

High levels of high-density lipoprotein cholesterol may increase the risk of diabetic kidney disease in patients with type 2 diabetes

Studies have indicated that low high-density lipoprotein cholesterol (HDL-C) level is an important risk factor for diabetic kidney disease (DKD) in patients with type 2 diabetes (T2D). However, whether higher HDL-C levels decrease the risk of developing DKD remains unclear. This study aimed to clarify the relationship between HDL-C levels and DKD risk in individuals with T2D in China. In total, 936 patients with T2D were divided into DKD and non-DKD groups. The association between HDL-C levels and DKD risk was evaluated using logistic regression analysis and restricted cubic spline curves adjusted for potential confounders. Threshold effect analysis of HDL-C for DKD risk was also performed. Higher HDL-C levels did not consistently decrease the DKD risk. Furthermore, a nonlinear association with threshold interval effects between HDL-C levels and the incidence of DKD was observed. Patients with HDL-C ≤ 0.94 mmol/L or HDL-C > 1.54 mmol/L had significantly higher DKD risk after adjusting for confounding factors. Interestingly, the association between high HDL-C levels and increased DKD risk was more significant in women. A U-shaped association between HDL-C levels and DKD risk was observed; therefore, low and high HDL-C levels may increase the DKD risk in patients with T2D.

Exploring the Relationship Between Atorvastatin and Memory Loss: A Comprehensive Analysis Integrating Real-World Pharmacovigilance and Mendelian Randomization

BACKGROUND AND OBJECTIVE

Atorvastatin is a drug widely used to prevent cardiovascular and cerebrovascular diseases. Current observational studies suggest that atorvastatin may be associated with cognitive dysfunction (especially memory loss). However, some studies have suggested that dyslipidemia may be an important factor in cognitive dysfunction. The purpose of this study was to perform a pharmacovigilance analysis using real-world data from the US Food and Drug Administration's Adverse Event Reporting System (FAERS) to assess whether memory loss is an adverse effect of atorvastatin and to further clarify its causality through Mendelian randomization (MR).

METHODS

We extracted real-world data from the FAERS database (Quarter 1 2004 to Quarter 1 2023). Disproportionality analysis methods and measures of association such as the reporting odds ratio (OR), proportional reporting ratio, Bayesian confidence interval progressive neural network, and polynomial Gamma Poisson distribution reduction were used to assess whether memory loss was an adverse effect of atorvastatin. In addition, we used MR to evaluate causality in depth.

RESULTS

In the pharmacovigilance analysis of atorvastatin, we extracted four datasets of clinical symptoms associated with memory loss from the FAERS database [Amnesia (n = 1196), Memory impairment (n = 840), Transient global amnesia (n = 38), and Retrograde amnesia (n = 9)]. The reporting OR, proportional reporting ratio, Bayesian confidence interval progressive neural network, and Gamma Poisson distribution reduction all showed positive results for amnesia, transient global amnesia, and retrograde amnesia, while the reporting OR and Bayesian confidence interval progressive neural network also showed positive results for memory disorders. Thus, memory loss was a frequent side effect of atorvastatin. The MR analyses were used to further evaluate the association between statins and memory loss. The results of the MR analysis (statins and memory loss) are as follows: Ivw (mre) (β = 0.11 [OR = 1.11], P = 0.01 < 0.05) and the OR and β directions of MR-Egger and weighted mode were the same. The results of the MR analysis (statins and mitochondrial DNA copy number) are as follows: Ivw(mre) (β = -0.03 [OR = 0.96], P < 0.01) and the OR and β direction of MR-Egger and weighted mode are the same. The results of the MR analysis (DNA copy number and memory loss) are as follows: Ivw(β = - 0.06 [OR = 0.94], P = 0.04 < 0.05) and the OR and β direction of MR-Egger and weighted mode were the same. The pleiotropy test did not find horizontal diversity in our results.

CONCLUSIONS

This study suggests that memory loss is a notable adverse event associated with atorvastatin and provides evidence indicating a potential causal relationship between atorvastatin and memory loss. We also found that statins may further affect memory by affecting mitochondrial function. Therefore, in the clinical use of atorvastatin, it is important to carefully monitor the changes in cognitive function of patients. Second, a pharmacovigilance analysis combined with MR was used in this study to provide a new approach for the study of adverse drug reactions. This comprehensive analysis method helps to evaluate the safety of drugs and the risk of adverse reactions more comprehensively and provides doctors with a more accurate clinical decision-making basis.

Transcriptome analysis combined with Mendelian randomization screening for biomarkers causally associated with diabetic retinopathy

Background

Diabetic retinopathy (DR) is considered one of the most severe complications of diabetes mellitus, but its pathogenesis is still unclear. We hypothesize that certain genes exert a pivotal influence on the progression of DR. This study explored biomarkers for the diagnosis and treatment of DR through bioinformatics analysis.

Methods

Within the GSE221521 and GSE189005 datasets, candidate genes were acquired from intersections of genes obtained using WGCNA and DESeq2 packages. Mendelian randomization (MR) analysis selected candidate biomarkers exhibiting causal relationships with DR. Receiver Operating Characteristic (ROC) analysis determined the diagnostic efficacy of biomarkers, the expression levels of biomarkers were verified in the GSE221521 and GSE189005 datasets, and a nomogram for diagnosing DR was constructed. Enrichment analysis delineated the roles and pathways associated with the biomarkers. Immune infiltration analysis analyzed the differences in immune cells between DR and control groups. The miRNet and networkanalyst databases were then used to predict the transcription factors (TFs) and miRNAs, respectively, of biomarkers. Finally, RT-qPCR was used to verify the expression of the biomarkers in vitro.

Results

MR analysis identified 13 candidate biomarkers that had causal relationships with DR. The ROC curve demonstrated favorable diagnostic performance of three biomarkers (OSER1, HIPK2, and DDRGK1) for DR, and their expression trends were consistent across GSE221521 and GSE189005 datasets. The calibration curves and ROC curves indicated good predictive performance of the nomogram. The biomarkers were enriched in pathways of immune, cancer, amino acid metabolism, and oxidative phosphorylation. Ten immune cell lines showed notable disparities between the DR and control groups. Among them, effector memory CD8+ T cells, plasmacytoid dendritic cells, and activated CD4+ T cells exhibited good correlation with biomarker expression. The TF-mRNA-miRNA network suggested that hsa-mir-92a-3p, GATA2, and RELA play important roles in biomarker targeting for DR. RT-qPCR results also demonstrated a notably high expression of HIPK2 in patients with DR, whereas notably low expression of OSER1.

Conclusion

OSER1, HIPK2, and DDRGK1 were identified as biomarkers for DR. The study findings provide novel insights into the pathogenesis of DR.

CAUSAL ROLES OF SERUM URIC ACID LEVELS AND GOUT IN SEPSIS: A MENDELIAN RANDOMIZATION STUDY

ABSTRACT

Objective: Several epidemiological studies have identified a potential link between serum uric acid (UA), gout, and sepsis. The primary objective of this study is to delve deeper into this connection, investigating the causal effect of UA and gout on sepsis by applying Mendelian randomization (MR). Methods: The causal relationship was analyzed using data from Genome-Wide Association Study (GWAS). Inverse variance weighting (IVW) was used as the main analysis method. Three complementary methods were used for our MR analysis, which included the MR-Egger regression method, the weighted median method, the simple median method. Horizontal pleiotropy was identified by MR-Egger intercept test. Cochran's Q statistics were employed to assess the existence of instrument heterogeneity. The leave-one-out method was used as a sensitivity analysis. Results: The IVW results indicated that there was a positive causal relationship between UA and sepsis (critical care) (odds ratio [OR] = 0.24, 95% confidence interval [CI]: 0.04 to 0.43, P = 0.018, F = 4,291.20). There was no significant association between UA and sepsis (28-day death in critical care) (OR = 0.10, 95% CI = -0.29 to 0.50, P = 0.604). There was no significant association between gout and sepsis (critical care) (OR = 0.85, 95% CI = -4.87 to 6.57, P = 0.771), and sepsis (28-day death in critical care) (OR = -6.30, 95% CI = -17.41 to 4.81, P = 0.267). Horizontal pleiotropy was absent in this study. The results were robust under all sensitivity analyses. Conclusion: The study revealed that elevated UA levels were causally linked with sepsis (critical care). No causal relationship had been found between UA and sepsis (28-day death in critical care), as well as between gout and sepsis.

SGLT2 inhibition, circulating proteins, and insomnia: A mendelian randomization study

BACKGROUND

Sodium-glucose cotransporter 2 inhibitors (SGLT2i) initially emerged as oral antidiabetic medication but were subsequently discovered to exhibit pleiotropic actions. Insomnia is a prevalent and debilitating sleep disorder. To date, the causality between SGLT2 inhibitors and insomnia remains unclear. This study aims to evaluate the causality between SGLT2 inhibitors and insomnia and identify potential plasma protein mediators.

METHODS

Using a two-sample Mendelian Randomization (MR) analysis, we estimated the causality of SGLT2 inhibition on insomnia and sleep duration. Additionally, employing a two-step and proteome-wide MR analysis, we evaluated the causal link of SGLT2 inhibition on 4907 circulating proteins and the causality of SGLT2 inhibition-driven plasma proteins on insomnia. We applied a false discovery rate (FDR) correction for multiple comparisons. Furthermore, mediation analyses were used to identify plasma proteins that mediate the effects of SGLT2 inhibition on insomnia.

RESULTS

SGLT2 inhibition was negatively correlated with insomnia (odds ratio [OR] = 0.791, 95 % confidence interval [CI] [0.715, 0.876], P = 5.579*10^-6) and positively correlated with sleep duration (β = 0.186, 95 % CI [0.059, 0.314], P = 0.004). Among the 4907 circulating proteins, diadenosine tetraphosphatase (Ap4A) was identified as being linked to both SGLT2 inhibition and insomnia. Mediation analysis indicated that the effect of SGLT2 inhibition on insomnia partially operates through Ap4A (β = -0.018, 95 % CI [-0.036, -0.005], P = 0.023), with a mediation proportion of 7.7 %.

CONCLUSION

The study indicated a causality between SGLT2 inhibition and insomnia, with plasma Ap4A potentially serving as a mediator.

Causal relationships between immune cell phenotypes and lung adenocarcinoma: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Lung adenocarcinoma (LUAD) is the most common type of lung cancer and closely associated with the immune system. Emerging evidence suggests that blood immune cell phenotypes in patients with LUAD may undergo alterations. Nevertheless, the limited amount of relevant research makes it difficult to understand the causal links between LUAD and changes in the immune cells. This study aimed to reveal the potential causal relationships between 731 immune cell phenotypes and LUAD.

METHODS

A bidirectional two-sample Mendelian randomization (MR) analysis was used to clarify causal relationships. Four types of immune phenotypes, absolute cell counts, relative cell counts, median fluorescence intensities (MFIs) of surface antigens, and morphological parameters, were investigated in this study. Heterogeneity tests, horizontal pleiotropy tests, and leave-one-out analyses were performed to validate the reliability of our study.

RESULTS

A total of 26 immune cell characteristics were identified as contributing to the occurrence of LUAD. Memory B cells, IgD-CD38br cells, CD4+ regulatory T cells (Tregs), and plasmacytoid dendritic cells (DCs) may play a role in the development of LUAD. Through reverse MR, our study discovered that the presence of LUAD also induced changes in the expression levels of 16 immune cell traits involving specific surface markers and various types of immune cells, some of which pertain to antigen presentation and immune activation processes.

CONCLUSION

Our study demonstrated causal links between several immune cell phenotypes and LUAD, thereby providing indications of the potentially oncogenic physiological state and early screening biomarkers for future research.

Causal relationship of interferon-γ and interleukin-18 upstream of intervertebral disc degeneration pathogenesis: a two-sample Mendelian randomization study

Introduction

Intervertebral disc degeneration (IVDD) is a complex disease caused by genetic and environmental factors, but its pathogenesis is still unclear. Although studies of inflammatory cytokines have been used in recent years to unravel the biological mechanisms of a variety of diseases, such analyses have not yet been applied to IVDD. Therefore, we used a Mendelian Randomization approach to explore the potential mechanisms underlying the pathogenesis of IVDD.

Methods

We obtained GWAS data from publicly available databases for inflammatory cytokines and IVDD, respectively, and explored the causal relationship between individual inflammatory cytokines and IVDD using instrumental variable (IV) analysis. We primarily used IVW methods to assess causality, while sensitivity, heterogeneity and multidirectionality analyses were performed for positive results (p < 0.05). All analyses were performed using R software.

Results

In our study, we performed a two-sample MR analysis of 41 inflammatory cytokines to identify metabolites causally associated with IVDD. Ultimately, 2 serum metabolites associated with IVDD were identified (pval<0.05), IFN-γ and IL-18. sensitivity, heterogeneity, and Pleiotropy test analyses were performed for all results.

Conclusion

Our study identified a causal relationship between IFN-γ and IL-18 and IVDD. It is valuable for the monitoring and prevention of IVDD and the exploration of targeted drugs. However, more evidence is needed to validate our study.

No Evidence of an Association between Genetic Factors Affecting Response to Vitamin A Supplementation and Myopia: A Mendelian Randomization Study and Meta-Analysis

The relationship between vitamin A supplementation and myopia has been a topic of debate, with conflicting and inconclusive findings. We aimed to determine whether there is a causal relationship between vitamin A supplementation and the risk of myopia using Mendelian randomization (MR) and meta-analytical methods. Genetic variants from the UK Biobank and FinnGen studies associated with the response to vitamin A supplementation were employed as instrumental variables to evaluate the causal relationship between vitamin A supplementation and myopia. Fixed-effects meta-analysis was then used to combine MR estimates from multiple sources for each outcome. The meta-analysis of MR results found no convincing evidence to support a direct causal relationship between vitamin A supplementation and myopia risk (odds ratio (OR) = 0.99, 95% confidence interval (CI) = 0.82-1.20, I2 = 0%, p = 0.40). The analysis of three out of the four sets of MR analyses indicated no direction of causal effect, whereas the other set of results suggested that higher vitamin A supplementation was associated with a lower risk of myopia (OR = 0.002, 95% CI 1.17 × 10-6-3.099, p = 0.096). This comprehensive MR study and meta-analysis did not find valid evidence of a direct association between vitamin A supplementation and myopia. Vitamin A supplementation may not have an independent effect on myopia, but intraocular processes associated with vitamin A may indirectly contribute to its development.

The association between fatty acids and atherosclerotic diseases: A mendelian randomization study

BACKGROUND

The current observational studies have disputed the relationship between various fatty acids and atherosclerotic diseases, and the causal relationship between the two is still unclear.

METHODS

In this study, we utilized the available genome-wide association studies (GWAS) summary data on fatty acids and atherosclerotic diseases from the IEU OpenGWAS project. After identifying the appropriate single nucleotide polymorphisms (SNPs) as instrumental variables, we employed the MR-PRESSO outlier test to remove extreme values. Subsequently, we conducted a two-sample mendelian randomization (MR) analysis and performed sensitivity analyses to ensure the reliability of the results.

RESULTS

The results of MR analysis suggest that ratio of saturated fatty acids to total fatty acids is positively correlated with the incidence rate of coronary heart disease (OR = 1.341, 95% CI = 1.016-1.769, P value = 0.038), monounsaturated fatty acid levels is negatively correlated with the incidence of stroke (OR = 0.800, 95% CI = 0.642-0.996, P value = 0.046), and docosahexaenoic acid levels is negatively correlated with the incidence of peripheral artery disease (OR = 0.747, 95% CI = 0.572-0.976, P value = 0.033). All results showed no heterogeneity or pleiotropy, but leave-one-out tests showed that the analysis results of some fatty acids were driven by a single SNP.

CONCLUSIONS

This study highlights the existence of causal relationships between fatty acids and atherosclerotic diseases at the genetic level. These findings provide valuable insights for potential prevention measures and therapeutic targets for the three atherosclerotic diseases.

Integrated mendelian randomization analyses highlight AFF3 as a novel eQTL-mediated susceptibility gene in renal cancer and its potential mechanisms

BACKGROUNDS

A growing number of expression quantitative trait loci (eQTLs) have been found to be linked with tumorigenesis. In this article, we employed integrated Mendelian randomization (MR) analyses to identify novel susceptibility genes in renal cancer (RC) and reveal their potential mechanisms.

METHODS

Two-sample MR analyses were performed to infer causal relationships between eQTLs, metabolites, and RC risks through the "TwoSampleMR" R package. Sensitivity analyses, such as heterogeneity, pleiotropy, and leave-one-out analysis, were used to assess the stability of our outcomes. Summary-data-based MR (SMR) analyses were used to verify the causal relationships among cis-eQTLs and RC risks via the SMR 1.3.1 software.

RESULTS

Our results provided the first evidence for AFF3 eQTL elevating RC risks, suggesting its oncogenic roles (IVW method; odds ratio (OR) = 1.0005; 95% confidence interval (CI) = 1.0001-1.0010; P = 0.0285; heterogeneity = 0.9588; pleiotropy = 0.8397). Further SMR analysis validated the causal relationships among AFF3 cis-eQTLs and RC risks (P < 0.05). Moreover, the TCGA-KIRC, the ICGC-RC, and the GSE159115 datasets verified that the AFF3 gene was more highly expressed in RC tumors than normal control via scRNA-sequencing and bulk RNA-sequencing (P < 0.05). Gene set enrichment analysis (GSEA) analysis identified six potential biological pathways of AFF3 involved in RC. As for the potential mechanism of AFF3 in RC, we concluded in this article that AFF3 eQTL could negatively modulate the levels of the X-11,315 metabolite (IVW method; OR = 0.9127; 95% CI = 0.8530-0.9765; P = 0.0081; heterogeneity = 0.4150; pleiotropy = 0.8852), exhibiting preventive effects against RC risks (IVW method; OR = 0.9987; 95% CI = 0.9975-0.9999; P = 0.0380; heterogeneity = 0.5362; pleiotropy = 0.9808).

CONCLUSIONS

We concluded that AFF3 could serve as a novel eQTL-mediated susceptibility gene in RC and reveal its potential mechanism of elevating RC risks via negatively regulating the X-11,315 metabolite levels.

Genetically predicted type 2 diabetes mellitus mediates the causal association between plasma uric acid and ischemic stroke

OBJECTIVE

This study conducts a systematic investigation into the causal relationships between plasma uric acid levels and subtypes of ischemic stroke (IS), as well as the extent to which Type 2 diabetes mellitus (T2DM) mediates this relationship.

BACKGROUND

There is a known association between Uric acid and IS but whether they have a causal relationship remains unclear. This study aims to determine whether a genetic predisposition to uric acid is causally linked to IS, including three subtypes, and to determine the mediating role of T2DM.

METHODS

Bidirectional Mendelian randomization (MR) analyses was initially used to explore the causal relationship between uric acid and three subtypes of IS. Two-step MR methods were then used to investigate the role of T2DM in mediating the effect of uric acid and IS with its subtypes.

RESULTS

A primary analysis showed uric acid had a markedly causal association with IS (IVW, OR 1.23; 95 % CI, 1.13 - 1.34; p = 6.39 × 10-9), and two subtypes of IS, Large-vessel atherosclerotic stroke LAS (IVW, OR 1.25; 95 % CI, 1.03 - 1.53; p = 0.026) and small vessel stroke (SVS) (IVW, OR 1.20; 95 % CI, 1.00 - 1.43; p = 0.049), but not with cardioembolic stroke (CES)(IVW, OR 1.00; 95 % CI, 0.87 - 1.15; p = 0.993). Two-step MR results showed that T2DM mediated the association between uric acid and LAS and SVS, accounting for 13.85 % (p = 0.025) and 13.57 % (p = 0.028), respectively.

CONCLUSIONS

The study suggests that genetic predisposition to uric acid is linked to a greater risk of IS, especially LAS and SVS. T2DM might mediate a significant proportion of the associations between uric acid and LAS as well as SVS.

A potentially underestimated predictor of coronary artery disease risk: The ApoB/ApoA1 ratio

Background

Cardiovascular disease (CVD) is the leading cause of death worldwide, and statin therapy is the cornerstone of atherosclerotic cardiovascular disease. However, clinical practice is unsatisfactory, and there is significant interest in the risk of residual cardiovascular events. Traditional study methods make it difficult to exclude the crosstalk of confounding factors, and we investigated the impact of the ApoB/ApoA1 ratio on CVD using two-sample Mendelian randomization (MR) and multivariate Mendelian randomization (MVMR) methods.

Methods

Two-sample MR and MVMR analyses were performed using pooled statistics from genome-wide association studies (GWAS) of ApoB/ApoA1 ratio (BAR), lipoprotein (a) (Lp(a)), and triglyceride (TG) in Europeans to assess the causal relationship between BAR, Lp(a), and TG with coronary artery disease (CAD).

Results

The genetic prediction of BAR was significantly correlated with CAD (Inverse variance weighted (IVW) beta = 0.255; OR = 1.291; 95 % CI = 1.061-1.571; P = 0.011) in a two-sample MR analysis. MVMR studies showed that BAR (beta = 0.373; OR = 1.452; 95 % CI = 1.305-1.615; P = 7.217e-12), Lp (a) (beta = 0.238; OR = 1.269; 95 % CI = 1.216-1.323; P = 2.990e-28), and TG (beta = 0.155; OR = 1.168; 95 % CI = 1.074-1.270; P = 2.829e-04) were significantly associated with CAD. After further colinearity analyses of LASSO regressions, the results of multivariate analyses were similar for IVW, MR-Egger, MR-Lasso, and median methods.

Conclusion

BAR is causally related to coronary artery disease. BAR is an independent predictor of CAD risk, independent of routine lipid measurements and other risk factors. TG and Lp(a) may be causally related to CAD, subject to verification in clinical practice.

Choice Function-Based Hyper-Heuristics for Causal Discovery under Linear Structural Equation Models

Causal discovery is central to human cognition, and learning directed acyclic graphs (DAGs) is its foundation. Recently, many nature-inspired meta-heuristic optimization algorithms have been proposed to serve as the basis for DAG learning. However, a single meta-heuristic algorithm requires specific domain knowledge and empirical parameter tuning and cannot guarantee good performance in all cases. Hyper-heuristics provide an alternative methodology to meta-heuristics, enabling multiple heuristic algorithms to be combined and optimized to achieve better generalization ability. In this paper, we propose a multi-population choice function hyper-heuristic to discover the causal relationships encoded in a DAG. This algorithm provides a reasonable solution for combining structural priors or possible expert knowledge with swarm intelligence. Under a linear structural equation model (SEM), we first identify the partial v-structures through partial correlation analysis as the structural priors of the next nature-inspired swarm intelligence approach. Then, through partial correlation analysis, we can limit the search space. Experimental results demonstrate the effectiveness of the proposed methods compared to the earlier state-of-the-art methods on six standard networks.

Correlation between hearing loss and mild cognitive impairment in the elderly population: Mendelian randomization and cross-sectional study

Background

Hearing loss and tinnitus have been linked to mild cognitive impairment (MCI); however, the evidence is constrained by ethical and temporal constraints, and few prospective studies have definitively established causation. This study aims to utilize Mendelian randomization (MR) and cross-sectional studies to validate and analyze this association.

Methods

This study employs a two-step approach. Initially, the genetic data of the European population from the Genome-wide association studies (GWAS) database is utilized to establish the causal relationship between hearing loss and cognitive impairment through Mendelian randomization using the inverse variance weighted (IVW) method. This is achieved by identifying strongly correlated single nucleotide polymorphisms (SNPs), eliminating linkage disequilibrium, and excluding weak instrumental variables. In the second step, 363 elderly individuals from 10 communities in Qingdao, China are assessed and examined using methods questionnaire survey and pure tone audiology (PTA). Logistic regression and multiple linear regression were used to analyze the risk factors of MCI in the elderly and to calculate the cutoff values.

Results

Mendelian randomization studies have shown that hearing loss is a risk factor for MCI in European populations, with a risk ratio of hearing loss to MCI loss of 1. 23. The findings of this cross-sectional study indicate that age, tinnitus, and hearing loss emerged as significant risk factors for MCI in univariate logistic regression analysis. Furthermore, multivariate logistic regression analysis identified hearing loss and tinnitus as potential risk factors for MCI. Consistent results were observed in multiple linear regression analysis, revealing that hearing loss and age significantly influenced the development of MCI. Additionally, a notable finding was that the likelihood of MCI occurrence increased by 9% when the hearing threshold exceeded 20 decibels.

Conclusion

This study provides evidence from genomic and epidemiological investigations indicating that hearing loss may serve as a risk factor for cognitive impairment. While our epidemiological study has found both hearing loss and tinnitus as potential risk factors for cognitive decline, additional research is required to establish a causal relationship, particularly given that tinnitus can manifest as a symptom of various underlying medical conditions.

A causal association between lipid-lowering medications and rotator cuff syndrome: a drug-targeted mendelian randomization study

Background: Previous research has suggested that dyslipidemia may be a risk factor for rotator cuff syndrome (RCS), and lipid-lowering drugs may aid in its treatment, though conclusions have not been definitive. Mendelian randomization is a statistical method that explores the causal relationships between exposure factors and diseases. It overcomes the confounding issues inherent in traditional observational studies, thereby providing more reliable causal inferences. We employed this method to investigate whether hyperlipidemia is a risk factor for rotator cuff syndrome and whether lipid-lowering drugs can effectively treat this condition. Methods: Genetic variations linked to lipid traits low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), and total cholesterol (TC) were acquired from the UK Biobank and the Global Lipids Genetics Consortium (GLGC). Data on genetic variation in rotator cuff syndrome were obtained from FinnGen, including 24,061 patients and 275,212 controls. In the next step, we carried out two-sample Mendelian randomization analyses to determine whether lipid traits correlate with rotator cuff syndrome risk. Additionally, we performed drug-target Mendelian randomization (MR) analyses on 10 drug targets related to rotator cuff syndrome. For the drug targets that showed significant results, further analysis was done using Summary-data-based Mendelian Randomization (SMR) and colocalization techniques. We performed a mediation analysis to identify potential mediators between HMG-CoA reductase (HMGCR) and RCS. Results: No causative link was established between these lipid traits and rotator cuff syndrome. However, a significant association has been identified where HMGCR inhibition corresponds to a reduced risk of rotator cuff disease (OR = 0.68, [95% CI, 0.56-0.83], p = 1.510 × 10-4). Additionally, enhanced expression of HMGCR in muscle tissues is also linked to a decreased risk of rotator cuff syndrome (OR = 0.88, [95% CI, 0.76-0.99], p = 0.03). Body mass index (BMI) mediated 22.97% of the total effect of HMGCR on RCS. Conclusion: This study does not support low-density LDL-C, TG, and TC as risk factors for rotator cuff syndrome. HMGCR represents a potential pharmaceutical target for preventing and treating rotator cuff syndrome. The protective action of statins on the rotator cuff syndrome might not be associated with their lipid-lowering properties.

Exploring gut microbiota's role in rheumatic valve disease: insights from a Mendelian randomization study and mediation analysis

Background

Investigating the relationship between gut microbiota and Rheumatic Valve Disease (RVD) is crucial for understanding the disease's etiology and developing effective interventions. Our study adopts a novel approach to examine the potential causal connections between these factors.

Methods

Utilizing a two-sample Mendelian Randomization (MR) framework, we incorporated a multi-variable MR (MVMR) strategy to assess the mediatory mechanisms involved. This approach involved analyzing data from the MiBioGen consortium for gut microbiota and the FinnGen for RVD, among other sources. Instrumental variables (IVs) were carefully selected based on rigorous MR principles, and statistical analysis was conducted using bidirectional two-sample MR, such as inverse variance-weighted (IVW), weighted median, MR-Egger regression and MR Steiger Test methods. The MR-PRESSO strategy was employed for outlier detection, and MVMR was used to untangle the complex relationships between multiple microbiota and RVD.

Results

Our analysis highlighted several gut microbiota classes and families with potential protective effects against RVD, including Lentisphaerae, Alphaproteobacteria, and Streptococcaceae. In contrast, certain genera, such as Eubacterium eligens and Odoribacter, were identified as potential risk factors. The MVMR analysis revealed significant mediation effects of various immune cell traits and biomarkers, such as CD4-CD8- T cells, CD3 on Terminally Differentiated CD8+ T cell and Pentraxin-related protein PTX, elucidating the complex pathways linking gut microbiota to RVD.

Conclusion

This study underscores the intricate and potentially causal relationship between gut microbiota and RVD, mediated through a range of immune and hormonal factors. The use of MVMR in our methodological approach provides a more comprehensive understanding of these interactions, highlighting the gut microbiota's potential as therapeutic targets in RVD management. Our findings pave the way for further research to explore these complex relationships and develop targeted interventions for RVD.

Causal relationship between immune cells and aortic aneurysms: a Mendelian randomization study

OBJECTIVES

The causal association between immune cell traits and aortic aneurysm remains unknown.

METHODS

We performed a bidirectional two-sample Mendelian randomization analysis to explore the causality between 731 immune cell characteristics and the risk of abdominal aortic aneurysm and thoracic aortic aneurysms through publicly available genetic data, respectively. To examine heterogeneity and horizontal pleiotropy, Cochran's Q test and MR-Egger intercept were utilized. Additionally, multivariable Mendelian randomization analysis and meta-analysis were performed in further analysis.

RESULTS

We found that 20 immune phenotypes had a suggestive causality on abdominal aortic aneurysm, and 15 immune phenotypes had a suggestive causal effect on thoracic aortic aneurysm. After further false discovery rate adjustment (q value <0.1), CD20 on IgD+ CD38- B cell (q = 0.053) and CD127 on CD28+ CD4+ T cell (q = 0.096) were associated with an increased risk of abdominal aortic aneurysm, respectively, indicating a significant causality between them. After adjusting for smoking, there is still statistical significance between CD127 on CD28+ CD4+ T cell and abdominal aortic aneurysm. However, after adjusting for lipids, no statistical significance can be observed between CD127 on CD28+ CD4+ T cells and abdominal aortic aneurysm. Furthermore, there is still statistical significance between CD20 on IgD+ CD38- B cells and abdominal aortic aneurysm after adjusting for lipids and smoking, which was further identified by meta-analysis.

CONCLUSIONS

We found a causal association between immune cell traits and aortic aneurysm by genetic methods, thus providing new avenues for future mechanism studies.

Genetically Determined Plasma Hepatocyte Growth Factor Levels Are Associated With the Risk and Prognosis of Ischemic Stroke

BACKGROUND

Observational studies suggest that hepatocyte growth factor (HGF) is associated with the risk and prognosis of ischemic stroke, but the causality of these associations remains unclear. Therefore, we conducted Mendelian randomization (MR) analyses to explore the associations of genetically determined plasma HGF levels with the risk and prognosis of ischemic stroke.

METHODS

A total of 13 single-nucleotide polymorphisms associated with plasma HGF were selected as genetic instruments based on the data from a genome-wide association study with 21 758 European participants. Summary data about the risk of ischemic stroke were obtained from the MEGASTROKE (Multiancestry Genome-Wide Association Study of Stroke) Consortium with 34 217 ischemic stroke cases and 406 111 controls of European ancestry, and summary data about the prognosis of ischemic stroke were obtained from the GISCOME study (Genetics of Ischaemic Stroke Functional Outcome) with 6165 European patients with ischemic stroke. We conducted an inverse-variance weighted Mendelian randomization analysis followed by a series of sensitivity analyses to evaluate the associations of genetically determined plasma HGF with the risk and prognosis of ischemic stroke.

RESULTS

The primary analyses showed that genetically determined high HGF was associated with an increased risk of ischemic stroke (odds ratio per SD increase, 1.11 [95% CI, 1.04-1.19]; P=1.10×10-3) and poor prognosis of ischemic stroke (odds ratio per SD increase, 2.43 [95% CI, 1.76-3.52]; P=6.35×10-8). In the secondary analysis, genetically determined plasma HGF was associated with a high risk of large atherosclerotic stroke (odds ratio per SD increase, 1.39 [95% CI, 1.18-1.63]; P=5.08×10-5) but not small vessel stroke and cardioembolic stroke. Mendelian randomization-Egger regression showed no directional pleiotropy for all associations, and the sensitivity analyses with different Mendelian randomization methods further confirmed these findings.

CONCLUSIONS

We found positive associations of genetically determined plasma HGF with the risk and prognosis of ischemic stroke, suggesting that HGF might be implicated in the occurrence and development of ischemic stroke.

Genetically identified mediators associated with increased risk of stroke and cardiovascular disease in individuals with autism spectrum disorder

Growing evidence suggested that individuals with autism spectrum disorder (ASD) associated with stroke and cardiovascular disease (CVD). However, the causal association between ASD and the risk of stroke and CVD remains unclear. To validate this, we performed two-sample Mendelian randomization (MR) and two-step mediation MR analyses, using relevant genetic variants sourced from the largest genome-wide association studies (GWASs). Two-sample MR evidence indicated causal relationships between ASD and any stroke (OR = 1.1184, 95% CI: 1.0302-1.2142, P < 0.01), ischemic stroke (IS) (OR = 1.1157, 95% CI: 1.0237-1.2160, P = 0.01), large-artery atherosclerotic stroke (LAS) (OR = 1.2902, 95% CI: 1.0395-1.6013, P = 0.02), atrial fibrillation (AF) (OR = 1.0820, 95% CI: 1.0019-1.1684, P = 0.04), and heart failure (HF) (OR = 1.1018, 95% CI: 1.0007-1.2132, P = 0.05). Additionally, two-step mediation MR suggested that type 2 diabetes mellitus (T2DM) partially mediated this effect (OR = 1.14, 95%CI: 1.02-1.28, P = 0.03). The mediated proportion were 10.96% (95% CI: 0.58%-12.10%) for any stroke, 11.77% (95% CI: 10.58%-12.97%) for IS, 10.62% (95% CI: 8.04%-13.20%) for LAS, and 7.57% (95% CI: 6.79%-8.36%) for HF. However, no mediated effect was observed between ASD and AF risk. These findings have implications for the development of prevention strategies and interventions for stroke and CVD in patients with ASD.

Uncovering Druggable Targets in Aortic Dissection: An Association Study Integrating Mendelian Randomization, pQTL, and Protein-Protein Interaction Network

Aortic dissection (AD) is a life-threatening acute aortic syndrome. There are limitations and challenges in the discovery and application of biomarkers and drug targets for AD. Mendelian randomization (MR) analysis is a reliable analytical method to identify effective therapeutic targets. We aimed to identify novel therapeutic targets for AD and investigate their potential side-effects based on MR analysis. Data from protein quantitative trait loci (pQTLs) were used for MR analyses to identify potential therapeutic targets. We probed druggable proteins involved in the pathogenesis of aortic dissection from deCODE. In this study, a two-sample MR analysis was conducted, with druggable proteins as the exposure factor and data on genome-wide association studies (GWAS) of AD as the outcome. After conducting a two-sample MR, summary data-based Mendelian randomization (SMR) analysis and colocalization analysis were performed. A protein-protein interaction (PPI) network was also constructed to delve into the interactions between identified proteins. After MR analysis and the Steiger test, we identified five proteins as potential therapeutic targets for AD. SMR analysis and colocalization analysis also confirmed our findings. Finally, we identified ASPN (OR = 1.36, 95% CI: 1.20, 1.54, p = 4.22 × 10-5) and SPOCK2 (OR = 0.57, 95% CI: 0.41, 0.78, p = 4.52 × 10-4) as the core therapeutic targets. Through PPI network analysis, we identified six druggable targets, enabling the subsequent identification of six promising drugs from DrugBank for treating AD. This discovery of specific proteins as novel therapeutic targets represents a significant advancement in AD treatment. These findings provide more effective treatment options for AD.

Omeprazole and risk of osteoarthritis: insights from a mendelian randomization study in the UK Biobank

BACKGROUND

A former cohort study has raised concern regarding the unanticipated hazard of omeprazole in expediting osteoarthritis (OA) advancement. The precise nature of their causal evidence, however, remains undetermined. The present research endeavors to investigate the underlying causal link between omeprazole and OA through the application of mendelian randomization (MR) analysis.

METHODS

The study incorporated the ukb-a-106 and ukb-b-14,486 datasets. The investigation of causal effects employed methodologies such as MR-Egger, Weighted median, Inverse variance weighted (IVW) with multiplicative random effects, and IVW (fixed effects). The IVW approach was predominantly considered for result interpretation. Sensitivity analysis was conducted, encompassing assessments for heterogeneity, horizontal pleiotropy, and the Leave-one-out techniques.

RESULTS

The outcomes of the MR analysis indicated a causal relationship between omeprazole and OA, with omeprazole identified as a contributing risk factor for OA development (IVW model: OR = 1.2473, P < 0.01 in ukb-a-106; OR = 1.1288, P < 0.05 in ukb-b-14,486). The sensitivity analysis underscored the robustness and dependability of the above-mentioned analytical findings.

CONCLUSION

This study, employing MR, reveals that omeprazole, as an exposure factor, elevates the risk of OA. Considering the drug's efficacy and associated adverse events, clinical practitioners should exercise caution regarding prolonged omeprazole use, particularly in populations with heightened OA risks. Further robust and high-quality research is warranted to validate our findings and guide clinical practice.

Adenosine 5'-Monophosphate-to-Threonine Ratio Promotes Abdominal Aortic Aneurysms via Up-Regulation of HLA-DR on Natural Killer Cells: A Bidirectional Mendelian Randomized Analysis

Objective: Immune-metabolic interactions may have causal and therapeutic impacts on abdominal aortic aneurysms (AAAs). However, due to the lack of research on the relationship between immune-metabolic interactions and AAAs, further exploration of the mechanism faces challenges. Methods: A two-sample, two-step mediation analysis with Mendelian randomization (MR) based on genome-wide association studies (GWASs) was performed to determine the causal associations among blood immune cell signatures, metabolites, and AAAs. The stability, heterogeneity, and pleiotropy of the results were verified using a multivariate sensitivity analysis. Results: After multiple two-sample MRs using the AAA data from two large-scale GWAS databases, we determined that the human leukocyte antigen-DR (HLA-DR) levels on HLA-DR + natural killer (NK) cells (HLA-DR/NK) were associated with the causal effect of an AAA, with consistent results in the two databases (FinnGen: odds ratio (OR) = 1.054, 95% confidence interval (CI): 1.003-1.067, p-value = 0.036; UK Biobank: OR = 1.149, 95% CI: 1.046-1.261, p-value = 0.004). The metabolites associated with the risk of developing an AAA were enriched to find a specific metabolic model. We also found that the ratio of adenosine 5'-monophosphate (AMP) to threonine could act as a potential mediator between the HLA/NK and an AAA, with a direct effect (beta effect = 0.0496) and an indirect effect (beta effect = 0.0029). The mediation proportion was 5.56%. Conclusions: Our study found that an up-regulation of HLA-DR on HLA-DR/NK cells can increase the risk of an AAA via improvements in the AMP-to-threonine ratio, thus providing a potential new biomarker for the prediction and treatment of AAAs.

Exploring Causal Relationships between Circulating Inflammatory Proteins and Thromboangiitis Obliterans: A Mendelian Randomization Study

BACKGROUND

 Thromboangiitis obliterans (TAO) is a vascular condition characterized by poor prognosis and an unclear etiology. This study employs Mendelian randomization (MR) to investigate the causal impact of circulating inflammatory proteins on TAO.

METHODS

 In this MR analysis, summary statistics from a genome-wide association study meta-analysis of 91 inflammation-related proteins were integrated with independently sourced TAO data from the FinnGen consortium's R10 release. Methods such as inverse variance weighting, MR-Egger regression, weighted median approaches, MR-PRESSO, and multivariable MR (MVMR) analysis were utilized.

RESULTS

 The analysis indicated an association between higher levels of C-C motif chemokine 4 and a reduced risk of TAO, with an odds ratio (OR) of 0.44 (95% confidence interval [CI]: 0.29-0.67; p = 1.4 × 10-4; adjusted p = 0.013). Similarly, glial cell line-derived neurotrophic factor exhibited a suggestively protective effect against TAO (OR: 0.43, 95% CI: 0.22-0.81; p = 0.010; adjusted p = 0.218). Conversely, higher levels of C-C motif chemokine 23 were suggestively linked to an increased risk of TAO (OR: 1.88, 95% CI: 1.21-2.93; p = 0.005; adjusted p = 0.218). The sensitivity analysis and MVMR revealed no evidence of heterogeneity or pleiotropy.

CONCLUSION

 This study identifies C-C motif chemokine 4 and glial cell line-derived neurotrophic factor as potential protective biomarkers for TAO, whereas C-C motif chemokine 23 emerges as a suggestive risk marker. These findings elucidate potential causal relationships and highlight the significance of these proteins in the pathogenesis and prospective therapeutic strategies for TAO.

Potential Mediating Role of Iron Biomarkers in the Association of Sex With Glucose, Insulin, and Type 2 Diabetes

Context

Sex-specific prevalence and incidence of type 2 diabetes (T2D) have been reported, but the underlying mechanisms are uncertain.

Objective

In this study, we aimed to investigate whether iron biomarkers mediate the association between biological sex and glucose metabolism and the incidence of T2D.

Methods

We used data from the general population enrolled in the prospective Prevention of REnal and Vascular ENd-stage Disease study in Groningen, The Netherlands. We measured ferritin, transferrin saturation (TSAT), hepcidin, soluble transferrin receptor (sTfR), fasting plasma glucose (FPG), fasting plasma insulin (FPI) levels, and incidence of T2D. We used multivariable regression and mediation analyses to investigate our hypothesis. All iron biomarkers, FPG, and FPI were log-transformed.

Results

The mean (SD) age of the 5312 (51.3% female) individuals was 52.2 (11.6) years. Compared with males, females had lower FPG (β = -.01; 95% CI -0.02, -0.01) and FPI (β = -.03; 95% CI -0.05, -0.02) levels. Ferritin, hepcidin, and sTfR showed potential mediating effects on the association between sex and FPG, 21%, 5%, and 7.1%, respectively. Furthermore, these variables mediated 48.6%, 5.7%, and 3.1% of the association between sex and FPI, respectively. Alternatively, TSAT had a suppressive mediating role in the association of sex with FPG and FPI. The incidence of T2D was lower in females than in males (hazard ratio 0.58; 95% CI 0.44, 0.77), with 19.2% of this difference being mediated by ferritin.

Conclusion

Iron biomarkers may partially mediate the association between sex and glucose homeostasis. Future studies addressing the causality of our findings are needed.

Mendelian randomization analysis reveals causal associations of serum metabolites with sepsis and 28-day mortality

Metabolic disorder has been found to be an important factor in the pathogenesis and progression of sepsis. However, the causation of such an association between serum metabolites and sepsis has not been established. We conducted a two-sample Mendelian randomization (MR) study. A genome-wide association study of 486 human serum metabolites was used as the exposure, whereas sepsis and sepsis mortality within 28 days were set as the outcomes. In MR analysis, 6 serum metabolites were identified to be associated with an increased risk of sepsis, and 6 serum metabolites were found to be related to a reduced risk of sepsis. Furthermore, there were 9 metabolites positively associated with sepsis-related mortality, and 8 metabolites were negatively correlated with sepsis mortality. In addition, "glycolysis/gluconeogenesis" (p = 0.001), and "pyruvate metabolism" (p = 0.042) two metabolic pathways were associated with the incidence of sepsis. This MR study suggested that serum metabolites played significant roles in the pathogenesis of sepsis, which may provide helpful biomarkers for early disease diagnosis, therapeutic interventions, and prognostic assessments for sepsis.

[Genetic Causation Analysis of Hyperandrogenemia Testing Indicators and Preeclampsia]

Objective

Some epidemiological studies have shown that pregnant women who develop preeclampsia (PE) have elevated levels of testosterone in their maternal plasma compared to women with normal blood pressure during pregnancy, revealing a potential association between hyperandrogenism in women and PE. To explore the causal relationship between hyperandrogenism and PE, this study selected total testosterone (TT), bioavailable testosterone (BIOT), and sex hormone binding globulin (SHBG) as exposure factors and PE and chronic hypertension with superimposed PE as disease outcomes. Two-sample Mendelian randomization (MR) analyses were used to genetically dissect the causal relationships between the three exposure factors (TT, BIOT, and SHBG) and the outcomes of PE and chronic hypertension with superimposed PE.

Methods

Two independent genome-wide association study (GWAS) databases were used for the two-sample MR analysis. In the GWAS data of female participants from the UK Biobank cohort, single nucleotide polymorphisms (SNPs) associated with TT, BIOT, and SHBG were analyzed, involving 230454, 188507, and 188908 samples, respectively. GWAS data on PE and chronic hypertension with superimposed PE from the Finnish database were used to calculate SNP, involving 3556 PE cases and 114735 controls, as well as 38 cases of chronic hypertension with superimposed PE and 114735 controls. To meet the assumptions of instrumental relevance and independence in MR analysis, SNPs associated with exposure were identified at the genome-wide level (P<5.0×10-8), and those in linkage disequilibrium interference were excluded based on clustering thresholds of R 2<0.001 and an allele distance greater than 10000 kb. Known confounding factors, including previous PE, chronic kidney disease, chronic hypertension, diabetes, systemic lupus erythematosus, or antiphospholipid syndrome, were also identified and the relevant SNPs were removed. Finally, we extracted the outcome data based on the exposure-related SNPs in the outcome GWAS, integrating exposure and outcome data, and removing palindromic sequences. Five genetic causal analysis methods, including inverse variance-weighted method (IVW), MR-Egger regression, weighted median method, simple mode method, and weighted mode method, were used to infer causal relationships. In the IVW, it was assumed that the selected SNPs satisfied the three assumptions and provided the most ideal estimate of the effect. IVW was consequently used as the primary analysis method in this study. Considering the potential heterogeneity among the instrumental variables, random-effects IVW was used for MR analysis. The results were interpreted using odds ratios (OR) and the corresponding 95% confidence interval (CI) to explain the impact of exposure factors on PE and chronic hypertension with superimposed PE. If the CI did not include 1 and had a P value less than 0.05, the difference was considered statistically significant. Sensitivity analysis was conducted to assess heterogeneity and pleiotropy. Heterogeneity was examined using Cochran's Q test, and pleiotropy was assessed using MR-Egger intercept analysis. Additionally, leave-one-out analysis was conducted to examine whether individual SNPs were driving the causal associations. To further validate the findings, MR analyses were performed using the same methods and outcome variables, but with different exposure factors, including waist-to-hip ratio adjusted for BMI (WHRadjBMI) and 25-hydroxyvitamin D levels, with MR results for WHRadjBMI and PE serving as the positive controls and MR results for 25-hydroxyvitamin D levels and PE as the negative controls.

Results

According to the criteria for selecting genetic instrumental variables, 186, 127, and 262 SNPs were identified as genetic instrumental variables significantly associated with testosterone indicators TT, BIOT, and SHBG. MR analysis did not find a causal relationship between the TT, BIOT, and SHBG levels and the risk of developing PE and chronic hypertension with superimposed PE. The IVW method predicted that genetically predicted TT (OR [95% CI]=1.018 [0.897-1.156], P=0.78), BIOT (OR [95% CI]=1.11 [0.874-1.408], P=0.392), and SHBG (OR [95% CI]=0.855 [0.659-1.109], P=0.239) were not associated with PE. Similarly, genetically predicted TT (OR [95% CI]=1.222 [0.548-2.722], P=0.624), BIOT (OR [95% CI]=1.066 [0.242-4.695], P=0.933), and SHBG (OR [95% CI]=0.529 [0.119-2.343], P=0.402) were not significantly associated with chronic hypertension with superimposed PE. Additionally, MR analysis using the MR-Egger method, weighted median method, simple mode method, and weighted mode method yielded consistent results, indicating no significant causal relationship between elevated testosterone levels and PE or chronic hypertension with superimposed PE. Heterogeneity was observed for SHBG in the analysis with PE (Cochran's Q test, P=0.01), and pleiotropy was detected for BIOT in the analysis with PE (MR-Egger intercept analysis, P=0.014), suggesting that the instrumental variables did not affect PE through BIOT. Other instrumental variables did not show significant heterogeneity or pleiotropy. Leave-one-out analysis confirmed that the results of the MR analysis were not driven by individual instrumental variables. Consistent with previous MR studies, the results of the control MR analyses using WHRadjBMI and 25-hydroxyvitamin D levels supported the accuracy of the MR analysis approach and the methods used in this study.

Conclusion

The MR analysis results suggest that current genetic evidence does not support a causal relationship between TT, BIOT, and SHBG levels and the development of PE and chronic hypertension with superimposed PE. This study suggests that elevated testosterone may be a risk factor for PE but not a direct cause.

Potential drug targets for tumors identified through Mendelian randomization analysis

According to the latest cancer research data, there are a significant number of new cancer cases and a substantial mortality rate each year. Although a substantial number of clinical patients are treated with existing cancer drugs each year, the efficacy is unsatisfactory. The incidence is still high and the effectiveness of most cancer drugs remains unsatisfactory. Therefore, we evaluated the human proteins for their causal relationship to for cancer risk and therefore also their potential as drug targets. We used summary tumors data from the FinnGen and cis protein quantitative trait loci (cis-pQTL) data from a genome-wide association study, and employed Mendelian randomization (MR) to explore the association between potential drug targets and nine tumors, including breast, colorectal, lung, liver, bladder, prostate, kidney, head and neck, pancreatic caners. Furthermore, we conducted MR analysis on external cohort. Moreover, Bidirectional MR, Steiger filtering, and colocalization were employed to validate the main results. The DrugBank database was used to discover potential drugs of tumors. Under the threshold of False discovery rate (FDR) < 0.05, results showed that S100A16 was protective protein and S100A14 was risk protein for human epidermal growth factor receptor 2-positive (HER-positive) breast cancer, phosphodiesterase 5A (PDE5A) was risk protein for colorectal cancer, and melanoma inhibitory activity (MIA) was protective protein for non-small cell lung carcinoma (NSCLC). And there was no reverse causal association between them. Colocalization analysis showed that S100A14 (PP.H4.abf = 0.920) and S100A16 (PP.H4.abf = 0.932) shared causal variation with HER-positive breast cancer, and PDE5A (PP.H4.abf = 0.857) shared causal variation with colorectal cancer (CRC). The MR results of all pQTL of PDE5A and MIA were consistent with main results. In addition, the MR results of MIA and external outcome cohort were consistent with main results. In this study, genetic predictions indicate that circulating S100 calcium binding protein A14 (S100A14) and S100 calcium binding protein A16 (S100A16) are associated with increase and decrease in the risk of HER-positive breast cancer, respectively. Circulating PDE5A is associated with increased risk of CRC, while circulating MIA is associated with decreased risk of NSCLC. These findings suggest that four proteins may serve as biomarkers for cancer prevention and as potential drug targets that could be expected for approval.

Causal effects and metabolites mediators between immune cell and risk of breast cancer: a Mendelian randomization study

Introduction: The incidence and mortality of female breast cancer remain high, and the immune microenvironment of breast cancer has undergone significant alterations. However, the impact of blood immune cell levels on the risk of breast cancer is not fully understood. Therefor this study aims to investigate the causal relationship between blood immune cell levels and the risk of breast cancer. Methods: A Mendelian randomization (MR) analysis was employed to assess the causal relationship between immune cells and the risk of breast cancer, as along with their potential mediating factors. Genetic statistics of metabolites breast cancer and immune cells were obtained from the GWAS Catalog, while the genome-wide association study (GWAS) statistics of breast cancer were extracted from the UK biobank. Two-sample MR analysis were performed using inverse-variance weighted (IVW) to ascertain the causal association between immune cells and the risk of breast cancer. Furthermore, 1,400 metabolites were analyzed for their mediating role between immune cells and the risk of breast cancer. Results: MR analysis through IVW method revealed that genetically predicted CD24+ CD27+ B cells were associated with a decreased risk of breast cancer (OR = 0.9978, 95% CI: 0.996-0.999, p = 0.001), while IgD- CD38+ B cells were linked to an increased risk of breast cancer (OR = 1.002, 95% CI: 1.001-1.004, p = 0.005). Additional CD14+ CD16+ monocytes were associated with an increased risk of breast cancer (OR = 1.000, 95% CI: 1.000-1.001, p = 0.005). Mediation analysis revealed a positive causal relationship between IgD- CD38+ B cells and Glycerate levels, with the latter also exhibiting a positive causal relationship with the risk of breast cancer (p < 0.05). Conversely, IgD- CD38+ B cells displayed a negative causal relationship with Succinoyltaurine levels, and the latter also demonstrated a negative causal relationship with the risk of breast cancer (p < 0.05). Conclusion: This MR study provides novel genetic evidence supporting a causal relationship between IgD- CD38+ B cells and the risk of BC. Moreover, it is identified that IgD- CD38+ B cells contribute to an increased risk of BC through both positive and negative mediation effects involving Glycerate and Succinoyltaurine.

Identification of cytokines in benign and malignant thymus tumors: based on Mendelian randomization and proteomics

Objective

The aim of this study was to identify potential causal cytokines in thymic malignancies and benign tumors from the FinnGen database using Mendelian randomization (MR).

Methods

In this study, data from genome-wide association studies (GWAS) of 91 cytokines were used as exposure factors, and those of thymic malignant tumors and thymic benign tumors were the outcome variables. Two methods were used to determine the causal relationship between exposure factors and outcome variables: inverse variance weighting (IVW) and MR-Egger regression. Sensitivity analysis was performed using three methods, namely, the heterogeneity test, the pleiotropy test, and the leave-one-out test.

Results

There was a causal relationship between the expression of fibroblast growth factor 5, which is a risk factor for thymic malignant tumors, and thymic malignant tumors. C-C motif chemokine 19 expression, T-cell surface glycoprotein CD5 levels, and interleukin-12 subunit beta levels were causally related to thymic malignant tumors and were protective. Adenosine deaminase levels, interleukin-10 receptor subunit beta expression, tumor necrosis factor (TNF)-related apoptosis-inducing ligand levels, and TNF-related activation-induced cytokine levels showed a causal relationship with thymic benign tumors, which are its risk factors. Caspase 8 levels, C-C motif chemokine 28 levels, interleukin-12 subunit beta levels, latency-associated peptide transforming growth factor beta 1 levels, and programmed cell death 1 ligand 1 expression showed a causal relationship with thymic benign tumors, which are protective factors. Sensitivity analysis showed no heterogeneity.

Conclusion

Cytokines showed a causal relationship with benign and malignant thymic tumors. Interleukin-12 subunit beta is a common cytokine that affects malignant and benign thymic tumors.

Exploring the causal association between genetically determined circulating metabolome and hemorrhagic stroke

Background

Hemorrhagic stroke (HS), a leading cause of death and disability worldwide, has not been clarified in terms of the underlying biomolecular mechanisms of its development. Circulating metabolites have been closely associated with HS in recent years. Therefore, we explored the causal association between circulating metabolomes and HS using Mendelian randomization (MR) analysis and identified the molecular mechanisms of effects.

Methods

We assessed the causal relationship between circulating serum metabolites (CSMs) and HS using a bidirectional two-sample MR method supplemented with five ways: weighted median, MR Egger, simple mode, weighted mode, and MR-PRESSO. The Cochran Q-test, MR-Egger intercept test, and MR-PRESSO served for the sensitivity analyses. The Steiger test and reverse MR were used to estimate reverse causality. Metabolic pathway analyses were performed using MetaboAnalyst 5.0, and genetic effects were assessed by linkage disequilibrium score regression. Significant metabolites were further synthesized using meta-analysis, and we used multivariate MR to correct for common confounders.

Results

We finally recognized four metabolites, biliverdin (OR 0.62, 95% CI 0.40-0.96, PMVMR = 0.030), linoleate (18. 2n6) (OR 0.20, 95% CI 0.08-0.54, PMVMR = 0.001),1-eicosadienoylglycerophosphocholine* (OR 2.21, 95% CI 1.02-4.76, PMVMR = 0.044),7-alpha-hydroxy-3 -oxo-4-cholestenoate (7-Hoca) (OR 0.27, 95% CI 0.09-0.77, PMVMR = 0.015) with significant causal relation to HS.

Conclusion

We demonstrated significant causal associations between circulating serum metabolites and hemorrhagic stroke. Monitoring, diagnosis, and treatment of hemorrhagic stroke by serum metabolites might be a valuable approach.

Genetic evidence strengthens the connection between gut microbiota and gingivitis: a two-sample Mendelian randomization study

Introduction

The oral cavity and gut tract, being interconnected and rich in microbiota, may have a shared influence on gingivitis. However, the specific role of distinct gut microbiota taxa in gingivitis remains unexplored. Utilizing Mendelian Randomization (MR) as an ideal method for causal inference avoiding reverse causality and potential confounding factors, we conducted a comprehensive two-sample MR study to uncover the potential genetic causal impact of gut microbiota on gingivitis.

Methods

Instrumental variables were chosen from single nucleotide polymorphisms (SNPs) strongly associated with 418 gut microbiota taxa, involving 14,306 individuals. Gingivitis, with 4,120 cases and 195,395 controls, served as the outcome. Causal effects were assessed using random-effect inverse variance-weighted, weighted median, and MR-Egger methods. For replication and meta-analysis, gingivitis data from IEU OpenGWAS were employed. Sensitivity analyses included Cochran's Q tests, funnel plots, leave-one-out analyses, and MR-Egger intercept tests. This study aimed to assess the genetic correlation between the genetically predicted gut microbiota and gingivitis using linkage disequilibrium score regression (LDSC).

Results

Three gut microbiota taxa (class Actinobacteria id.419, family Defluviitaleaceae id.1924, genus Defluviitaleaceae UCG011 id.11287) are predicted to causally contribute to an increased risk of gingivitis (P< 0.05). Additionally, four gut microbiota taxa (class Actinobacteria id.419, genus Escherichia Shigella id.3504, genus Ruminococcaceae UCG002 id.11360) potentially exhibit inhibitory causal effects on the risk of gingivitis (P< 0.05). No significant evidence of heterogeneity or pleiotropy is detected. Our findings indicate a suggestive genetic correlation between class Actinobacteria id.419, class Bacteroidia id.912, family Defluviitaleaceae id.1924, genus Escherichia Shigella id.3504 and gingivitis.

Conclusion

Our study establishes the genetic causal effect of 418 gut microbiota taxa on gingivitis, offering insights for clinical interventions targeting gingivitis. Subsequent research endeavors are essential to corroborate the findings of our present study.

Causal relationship between type 2 diabetes mellitus and aortic dissection: insights from two-sample Mendelian randomization and mediation analysis

Objective

Some evidence suggests a reduced prevalence of type 2 diabetes mellitus (T2DM) in patients with aortic dissection (AD), a catastrophic cardiovascular illness, compared to general population. However, the conclusions were inconsistent, and the causal relationship between T2DM and AD remains unclear.

Methods

In this study, we aimed to explore the causal relationship between T2DM and AD using bidirectional Mendelian randomization (MR) analysis. Mediation MR analysis was conducted to explore and quantify the possible mediation effects of 1400 metabolites in T2DM and AD.

Results

The results of 26 datasets showed no causal relationship between T2DM and AD (P>0.05). Only one dataset (ebi-a-GCST90006934) showed that T2DM was a protective factor for AD (I9-AORTDIS) (OR=0.815, 95%CI: 0.692-0.960, P=0.014), and did not show horizontal pleiotropy (P=0.808) and heterogeneity (P=0.525). Vanillic acid glycine plays a mediator in the causal relationship between T2DM and AD. The mediator effect for vanillic acid glycine levels was -0.023 (95%CI: -0.066-0.021).

Conclusion

From the perspective of MR analysis, there might not be a causal relationship between T2DM and AD, and T2DM might not be a protective factor for AD. If a causal relationship does exist between T2DM and AD, with T2DM serving as a protective factor, vanillic acid glycine may act as a mediator and enhance such a protective effect.

Unraveling genetic causality between metformin and myocardial infarction on the basis of Mendelian randomization

Background

In recent years, several studies have explored the effect of metformin on myocardial infarction (MI), but whether metformin has an improvement effect in patients with MI is controversial. This study was aimed to investigate the causal relationship between metformin and MI using Mendelian randomization (MR) analysis.

Methods

The genome-wide significant (P<5×10-8) single-nucleotide polymorphisms (SNPs) in patients with metformin and patients with MI were screened from the Open genome-wide association study (GWAS) project as instrumental variables (IVs). The study outcomes mainly included MI, old MI, acute MI, acute transmural MI of inferior wall, and acute transmural MI of anterior wall. The inverse variance weighted (IVW) method was applied to assess the main causal effect, and weighted median, simple mode, weighted mode methods, and MR-Egger regression were auxiliary applied for supplementary proof. The causal relationship between metformin and MI was assessed using odds ratios (OR) and 95% confidence intervals (95% CI). A leave-one-out method was used to explore the effect of individual SNPs on the results of IVW analyses, and a funnel plot was used to analyze the potential bias of the study results, thus ensuring the robustness of the results.

Results

In total, 16, 84, 39, 26, and 34 SNPs were selected as IVs to assess the genetic association between metformin and outcomes of MI, old MI, acute MI, acute transmural MI of inferior wall, and acute transmural MI of anterior wall, respectively. Treatment with metformin does not affect the risk of acute transmural MI of anterior wall at the genetic level (P>0.05; OR for inverse variance weighted was 1.010). In the cases of MI, old MI, acute MI, and acute transmural MI of inferior wall, metformin may even be a risk factor for patients (P<0.05; ORs for inverse variance weighted were 1.078, 1.026, 1.022 and 1.018 respectively). There was no horizontal pleiotropy or heterogeneity among IVs. The results were stable when removing the SNPs one by one.

Conclusion

Metformin is not protective against the risk of myocardial infarction in patients and may even be a risk factor for MI, old MI, acute MI, and acute transmural MI of inferior wall.

The causal relationship between metabolic syndrome and its components and cardiovascular disease: A mendelian randomization study

AIM

To investigate the causal relationship between metabolic syndrome (MetS) and its components and 14 cardiovascular diseases using Mendelian randomization (MR).

METHODS

We used summary statistics from large-scale genome-wide association studies of MetS, its components, and cardiovascular diseases. We performed a two-sample MR analysis using the inverse-variance weighted method and other sensitivity methods. We also performed multivariate MR to adjust for potential risk factors.

RESULTS

Our study found that MetS was causally associated with an increased risk of ischemic stroke, abdominal aortic aneurysm, pulmonary embolism, coronary heart disease, heart failure, and peripheral artery disease. Waist circumference was causally associated with an increased risk of 6 cardiovascular diseases. Type 2 diabetes mellitus, diastolic blood pressure, systolic blood pressure, triglycerides, and high-density lipoprotein cholesterol were all causally associated with coronary heart disease, with varying causal relationships with the remaining 5 cardiovascular diseases. Multivariate MR showed that, except for ischaemic stroke, waist circumference remained causally associated with the remaining five cardiovascular diseases after adjusting for potential confounders.

CONCLUSION

Our study provides evidence that metabolic syndrome is causally associated with 6 cardiovascular diseases. Waist circumference is the most important component of these relationships. These findings have implications for the prevention and management of metabolic syndrome and cardiovascular diseases.

Genetically predicted lipids mediate the association between intrahepatic cholestasis of pregnancy and cardiovascular disease

Introduction

Intrahepatic cholestasis of pregnancy (ICP), the most prevalent liver disorder specific to pregnancy, affects approximately 1.5%-4% of pregnancies. However, the influence of ICP on cardiovascular disease (CVD), including hypertension (HTN) and coronary artery disease (CAD), has not been thoroughly investigated.

Methods

This study explores the causal relationship between ICP and CVD (HTN, CAD) using Mendelian Randomization (MR). Utilizing summary-level data from Genome-Wide Association Studies (GWAS), we applied the inverse-variance weighted (IVW) method, supplemented by sensitivity and reverse MR analyses, to ascertain robustness.

Results

Our findings reveal significant causal links, indicating ICP notably increases the risk of CVD (P = 0.001), hypertension (HTN, P = 0.024), and coronary artery disease (CAD, P = 0.039). A two-step MR analysis highlighted the mediation role of lipid profiles, with LDL, TC, and Apo-B contributing to increased CVD risk by 25.5%, 12.2%, and 21.3%, respectively. Additionally, HTN was identified as a mediator in the ICP-CAD association, accounting for a 14.5% mediation effect.

Discussion

The results underscore the genetic predisposition of ICP to elevate CVD risk and the critical mediating role of lipid levels, emphasizing the need for vigilant lipid monitoring and early intervention in individuals with ICP.