'Mendelian randomization': can genetic epidemiology contribute to understanding environmental determinants of disease?

The association between fatigue and cardiometabolic diseases: Insights from the UK biobank study

BACKGROUND

Cardiometabolic diseases (CMD) are major global health concerns with significant morbidity and mortality. Fatigue, a common but often overlooked symptom, has been postulated as both a potential risk factor for and a consequence of these conditions. However, the relationships between fatigue and CMD remain unclear. This study aimed to investigate the relationship between fatigue and CMD using observational and genetic approaches.

METHOD

Observational study was conducted in the UK biobank. Genetic method was employed a bidirectional MR approach to examine the causal relationship between fatigue and CMD. Genetic variants associated with fatigue were identified through a GWAS, and summary statistics from the largest available GWAS were used to obtain variants associated with stroke, CAD, T2D, and HF. Inverse variance weighting (IVW) was conducted, with weighted median, MR-Egger, and MR-PRESSO as sensitivity analyses. Multivariable MR and mediation analysis were also employed.

RESULTS

Observational analyses indicated that individuals with fatigue had a significantly increased risk of developing stroke (HR 1.44, 95 % CI 1.27-1.63), T2D (HR 1.46, 95 % CI 1.41-1.51), CAD (HR 1.45, 95 % CI 1.4-1.5), and HF (HR 1.60, 95 % CI 1.52-1.68). Mendelian randomization analyses further supported a causal relationship. Additionally, observational and genetic analyses showed T2D was found to be associated with increased levels of fatigue. Mediation analysis identified lipid metabolites as mediators in the relationship between fatigue and CMD.

CONCLUSION

This study highlights a bidirectional relationship between fatigue and CMD, underscoring the importance of considering fatigue in the context of cardiometabolic health.

CLINICAL TRIAL NUMBER

Not applicable.

Association between frailty and common psychiatric disorders: A bidirectional Mendelian randomization study

BACKGROUND

There is growing interest in exploring the relationship between frailty and common psychiatric disorders. However, there have been limited reports on the genetic variation level of frailty with psychiatric disorders.

METHOD

We conducted large-scale Two-sample Mendelian randomization (MR) analyses to examine whether there is an association between frailty and common psychiatric disorders (bipolar disorder [BD], major depressive disorder [MDD], schizophrenia, and suicide or other Intentional self-harm). We employed multiple MR approaches to conduct the MR analysis, including MR-Egger, weighted median, and random-effect inverse variance weighted (IVW). The IVW method served as the primary analysis. Heterogeneity testing and sensitivity analysis were also conducted in the MR study.

RESULTS

The MR results denoted that frailty was associated with an increased risk of BD (odds ratio (OR) =1.60, PIVW = 0.017), MDD (OR = 2.04, PIVW < 0.001), schizophrenia (OR = 1.91, PIVW = 0.005), and suicide or other Intentional self-harm (OR = 1.77, PIVW < 0.001). For reverse analysis, we observed no significant association between psychiatric disorders and the risk of frailty. These results remained consistent across sensitivity assessments.

CONCLUSIONS

Our research indicates a potential unidirectional causal relationship, suggesting that frailty may serve as a risk factor for certain common psychiatric disorders. These findings carry important for implications for psychiatric disorders and frailty patient care.

The impact of cathepsins on liver hepatocellular carcinoma: Insights from genetic and functional analyses

Liver Hepatocellular Carcinoma (LIHC), ranked as the second deadliest cancer globally, poses a major health challenge because of its widespread occurrence and poor prognosis. The mechanisms underlying LIHC development and progression remain unclear. Cathepsins are linked to tumorigenesis in other cancers, but their role in LIHC is underexplored. This study employed integrative analyses, including Mendelian Randomization (MR), bulk RNA-sequencing (bulk-seq), single-cell RNA sequencing (scRNA-seq), immunohistochemical (IHC) analysis, and cellular experiments with siRNA technology, to investigate the role of cathepsin E (CTSE) in LIHC. MR analysis identified CTSE as a factor associated with increased LIHC risk. Prognostic analysis using TCGA data showed that higher CTSE levels are linked to poorer survival, establishing CTSE as an independent prognostic risk factor. Integrative transcriptome analysis revealed close relation of CTSE to the extracellular matrix. scRNA-seq from TISCH2 demonstrated that CTSE is predominantly expressed in malignant LIHC cells. IHC confirmed higher CTSE expression in LIHC tissues compared to peritumoral tissues. Functional assays, such as qRT-PCR, Western blot, cell proliferation, and colony formation experiments, demonstrated that siRNA-mediated CTSE knockdown in HepG2 and Huh7 cell lines notably suppressed cell proliferation and altered the FAK/Paxillin/Akt signaling cascade. This research enhances our comprehension of LIHC development, emphasizing CTSE as a promising prognostic marker and potential therapeutic target. Inhibiting CTSE could slow the progression of LIHC, presenting novel opportunities for therapeutic approaches.

Study on the activity and mechanism of herbal formula anti-infection powder (AIP) against influenza-virus-induced pneumonia through genetic susceptibility genes

ETHNOPHARMACOLOGICAL RELEVANCE

Anti-infection powder (AIP), a patented Chinese herbal formulation, is used traditionally in the treatment of upper respiratory tract infections. In this study, an ethanol extract of AIP was demonstrated to inhibit influenza A virus (IAV) infection and IAV-induced pneumonia (IVP), both in vitro and in vivo, highlighting its potential mechanism of action.

AIM OF THE STUDY

To determine the anti-IAV activity of AIP and to explore the possible mechanisms of inhibiting IAV-induced pneumonia.

MATERIALS AND METHODS

An ethanol extract was extracted from AIP and its major ingredients were determined by high-performance liquid chromatography (HPLC). An IAV-infected A549 cell model and an IAV-induced mouse pneumonia model were established to evaluate the therapeutic effects of AIP on IVP in vivo and in vitro. The mice were respectively administered AIP at high- and low-dose in different groups. The anti-IAV activity of AIP was evaluated by detecting viral load, lung lesion, lung index, suvival time, inflammatory cytokines and transcriptomic analysis in the lung tissue. The potential pathways and targets that involved in AIP against IVP were predicted by network pharmacology. Mendelian randomization (MR), colocalization analysis, and molecular docking were employed to identify novel therapeutic targets for IVP. Polymerase chain reaction (PCR) and Western blot (WB) techniques were used to confirm the effect of AIP on the expression of risk target genes in the lungs of IVP mice.

RESULTS

In A549 cell line, AIP effectively inhibited IAV infection with IC50 values of 65.49 μg/mL. The anti-IAV activity of AIP was mainly determined by chlorogenic acid, forsythiarin, puerarin, paeoniflorin and prim-o-glucosylcimigin. Moreover, AIP inhibited the neuraminidase activity and the M gene expression in vitro. In vivo, oral administration of AIP significantly reduced viral load and improved lung tissue lesions. AIP decreased the concentration of pro-inflammatory factors such as IL-1β, TNF-α, and IFN-γ, and significantly increased the concentration of the anti-inflammatory factor IL-4. According to network pharmacology analysis, toll-like receptor signaling pathway, chemokine signaling pathway, and TNF signaling pathway may be the possible mechanisms by which AIP inhibits IVP and regulates excessive inflammatory response.Two new genes, LRG1 and PSMA4, associated with genetic susceptibility to influenza and pneumonia, predicted as potential IVP drug target genes by MR and colocalization analysis. The antiviral mechanism of AIP may be to inhibit the expression levels of LRG1 and PSMA4 in lungs of mouse IVP.

CONCLUSIONS

AIP exhibited anti-IAV activities both in vitro and in vivo. AIP had a protective effect against pneumonia caused by influenza virus and can inhibit the progression of inflammation. This effect may be associated with its ability to inhibit the expression levels of genetic susceptibility genes (LRG1 and PSMA4) in lungs of mouse IVP. The findings of this study enhance our understanding of the role and mechanisms of AIP in the treatment of IVP.

Sarcopenia and immune-mediated inflammatory diseases: Evaluating causality and exploring therapeutic targets for sarcopenia through Mendelian randomization

BACKGROUND

An increasing body of evidence has revealed the association between immune-mediated inflammatory diseases (IMIDs) and sarcopenia. However, a genetically direct causality between IMIDs and sarcopenia remains elusive.

METHODS

To investigate the relationship between IMIDs and sarcopenia-related traits and identify potential therapeutic targets, a Mendelian randomization (MR) was performed. We collected publicly available genome-wide association studies (GWAS) data for seven common IMIDs, including systemic lupus erythematosus (SLE), inflammatory bowel disease (IBD), Crohn's disease (CD), ulcerative colitis (UC), psoriasis (PSO), ankylosing spondylitis (AS), and rheumatoid arthritis (RA). Additionally, summary-level GWAS data for sarcopenia-related traits, including appendicular lean mass (ALM), left-hand grip strength, and right-hand grip strength were collected. To search for therapeutic targets, we used two types of genetic instruments to proxy the exposure of druggable genes, including genetic variants within or nearby drug targets and expression quantitative trait loci (eQTLs) of drug targets. Two-sample MR and summary-data-based MR (SMR) were used to calculate effect estimates, and sensitivity analyses were implemented for robustness. Drug tractability, gene enrichment analysis, and protein-protein interaction (PPI) analysis were used to validate the biological and clinical significance of the selected drug targets.

RESULTS

The two-sample MR analysis indicated the existence of casual associations between IMIDs and sarcopenia-related traits in the overall and sex-stratified populations. In particular, PSO had causal effects on decreased ALM, which showed significance in all six MR analysis tests with directional consistency in the overall population. Grounded in this robust association, HLA-DRB5, HLA-DRB1, and AGER were identified as potential therapeutic targets for ALM decline by drug target MR and further confirmed by SMR analysis. These genes were associated with therapeutic agents currently undergoing evaluations in clinical trials. Gene enrichment and PPI analysis indicated a strong association of these genes with immune functions.

CONCLUSIONS

This MR study contributes novel genetic evidence supporting the causal link between IMIDs and sarcopenia, with a particular emphasis on the association between PSO and decreased ALM. Additionally, AGER, HLA-DRB1, and HLA-DRB5 emerge as potential therapeutic targets for ALM decline.

Exploration of potential drug targets for Glaucoma by plasma proteome screening

BACKGROUND

Glaucoma is the leading cause of irreversible blindness. However, the current available treatment methods are still unsatisfactory. Therefore, the exploration of new drug targets for the treatment of glaucoma is of paramount importance.

METHODS

We conducted two-sample Mendelian randomization (MR) using plasma protein quantitative trait loci (pQTL) data from two datasets (n = 734, n = 4907) and their instrumental variables to investigate the causal relationship between plasma proteins and glaucoma. The analysis was validated by replacing the exposure and outcome cohorts. Additionally, we utilized protein-protein interaction networks to assess the associations between these potential drug targets and existing drug targets.

RESULTS

Through two-sample Mendelian randomization analysis, we identified causal relationships between Glaucoma and the following proteins: AZU1, OBP2B, ENPP5, INPP5B, KREMEN1, LYPLAL1, and PTPRJ. External validation confirmed the protective effect of LYPLAL1 on Glaucoma, while ENPP5, KREMEN1, and PTPRJ increased the risk of Glaucoma. Reverse MR and Steiger filtering did not indicate any reverse causal associations of the aforementioned proteins with Glaucoma.

CONCLUSION

Our study demonstrates a causal impact of ENPP5, KREMEN1, PTPRJ, and LYPLAL1 on the risk of Glaucoma. These findings suggest that these four proteins may serve as promising drug targets for Glaucoma treatment.

SIGNIFICANCE

Currently, the pharmacological treatment of glaucoma primarily focuses on lowering intraocular pressure, which has its limitations. Targeted therapy is a personalized treatment approach that aims to inhibit or block the development and progression of diseases such as cancer and inflammation by selectively acting on specific biomolecules or signaling pathways. Our research employs a two-sample Mendelian randomization (MR) method, integrating a large amount of GWAS and pQTL data to perform MR analysis. This has enabled us to explore several plasma proteins as potential drug targets for glaucoma, providing direction and a research foundation for future investigations into glaucoma drug targets.

Socioeconomic status, individual behaviors and risk of anxiety disorders: A Mendelian randomization study

BACKGROUND

The association between socioeconomic status and individual behaviors (SES/IB) and anxiety disorders has garnered increasing attention, yet the impact of SES/IB on anxiety disorders remains unclear. Therefore, we employed a Mendelian randomization (MR) design to evaluate the causal relationship between SES/IB and anxiety disorders.

METHODS

We conducted a two-sample MR study to assess the causal effects of SES and IB (smoking behaviors, drinking behaviors, sleeping behaviors, habitual physical activity, leisure sedentary behaviors, and reproductive behaviors) on anxiety disorders. A series of filtering steps were taken to select eligible genetic instruments robustly associated with each of the traits. The inverse variance weighted was used for preliminary analysis, and multiple methods were used for sensitivity testing.

RESULTS

After Bonferroni correction and rigorous quality control, we found that educational attainment (odds ratio [OR]:0.75; 95 % confidence interval [CI]:0.69-0.81; P = 9.21E-12), alcohol consumption per week (OR: 1.62; 95 % CI: 1.33-1.97; P = 1.80E-06), insomnia (OR: 1.68; 95 % CI: 1.43-1.97; P = 1.45E-10),age at first birth (OR: 0.59; 95 % CI: 0.50-0.68; P = 1.31E-11),and number of sexual partners (OR: 2.19; 95 % CI: 1.71-2.80; P = 6.64E-10) were causally associated with anxiety disorders.

LIMITATIONS

The subjects included in this study were all of European descent, and whether this finding can be generalized to other populations needs to be further demonstrated.

CONCLUSIONS

The MR Study provides strong evidence that some factors influence anxiety disorders.

Mendelian randomization and transcriptomic analysis reveal a positive cause-and-effect relationship between Alzheimer's disease and colorectal cancer

BACKGROUND

This study addresses the complex multifactorial causes of Alzheimer's disease (AD) and colorectal cancer (CRC), two significant public health issues. Despite previous research, the precise relationship between AD and CRC remains unclear. This study aimed to explore the potential causal relationship between AD and CRC using Mendelian randomization (MR) and to identify risk genes through colocalization and transcriptomic analyses.

METHOD

The study used a two-sample Mendelian randomization (MR) approach to investigate the causal effect of AD on CRC. Genome-wide association study (GWAS) summary statistics for AD and CRC were utilized. Colocalization analysis was conducted to identify risk genes associated with AD, which were then validated through transcriptomic analysis in CRC samples. The study used GWAS data from a cohort of European patients and applied several MR methods, including MR Egger, weighted median, and inverse-variance weighted approaches, to ensure robust findings.

RESULTS

The MR analysis revealed a significant positive causal relationship between AD and CRC, indicating that an increased genetic predisposition to AD is associated with a elevated risk of developing CRC. The colocalization analysis identified COLEC11 as a significant risk gene for AD, which also showed a strong positive correlation with clinical features and survival outcomes in CRC. Elevated COLEC11 expression was linked to advanced clinical stages, increased tumor mutational burden, microsatellite instability, and poorer overall survival in CRC patients.

CONCLUSIONS

This study provides evidence of a causal relationship between AD and CRC, suggesting that shared genetic and inflammatory pathways may underlie both conditions. The identification of COLEC11 as a potential link between AD and CRC offers new avenues for research and therapeutic interventions. These findings contribute to a deeper understanding of the interplay between neurodegenerative and oncologic diseases, highlighting the importance of exploring common pathogenic mechanisms.

Lifelong impacts of puberty timing on human plasma metabolic profiles: A metabolome-wide Mendelian randomization study

AIM

The aim was to investigate the causal relationship between puberty timing and plasma metabolites, accounting for birth weight, childhood and adulthood adiposity.

MATERIALS AND METHODS

The meta-analysis of genome-wide association studies (GWAS) for puberty timing was extracted from the ReproGen Consortium, involving 329 345 women of European ancestry. Summary data for 174 plasma metabolites were retrieved from a recently conducted cross-platform GWAS that involved a meta-analysis of three cohort studies (i.e. the Fenland, European Prospective Investigation into Cancer-Norfolk and INTERVAL studies) and three publicly available studies and included up to 86 507 participants. We conducted a two-sample Mendelian randomization (MR) analysis to infer the causal relationship of puberty timing on 174 plasma metabolites, complemented by a two-step and multivariable Mendelian randomization (MVMR) analysis to assess direct and indirect effects. Additionally, summary-level data from the UK Biobank were used for our replication analysis.

RESULTS

The results of the two-sample MR provide moderate evidence supporting a causal relationship between puberty timing and 23 of 174 plasma metabolites (i.e. 7 acylcarnitines, 8 amino acids, 2 biogenic amines and 6 lysophosphatidylcholines). Even after single-nucleotide polymorphisms associated with birth weight and childhood adiposity were excluded, causal effects persisted for 16 metabolites (i.e. 8 acylcarnitines, 4 amino acids, 2 biogenic amines and 2 lysophosphatidylcholines). The two-step MR analysis provided evidence that the relationship between puberty timing and plasma metabolites was mediated by adulthood adiposity. Additionally, moderate evidence emerged for an independent causal effect of puberty timing on 10 metabolites through an MVMR analysis (i.e. 5 acylcarnitines, 2 amino acids, 1 biogenic amine, 1 lysophosphatidylcholine and 1 phosphatidylcholine). Furthermore, the replication analysis suggested the robustness of our results.

CONCLUSIONS

In summary, our study provides compelling evidence that puberty timing has a causal influence on certain plasma metabolites, although this influence is largely mediated by adulthood adiposity.

Causal Associations of Cognitive Reserve and Hierarchical Aging-Related Outcomes: A Two-Sample Mendelian Randomization Study

PURPOSE

Two-sample Mendelian randomization methods were used to explore the causal effects of cognitive reserve proxies, such as educational attainment, occupational attainment, and physical activity (PA), on biological (leukocyte telomere length), phenotypic (sarcopenia-related features), and functional (frailty index and cognitive performance) aging levels.

RESULTS

Educational attainment had a potential protective effect on the telomere length (β = 0.10, 95% CI: 0.08-0.11), sarcopenia-related features (β = 0.04-0.24, 95% CI: 0.02-0.27), frailty risk (β = -0.31, 95% CI: -0.33 to -0.28), cognitive performance (β = 0.77, 95% CI: 0.75-0.80). Occupational attainment was causally related with sarcopenia-related features (β = 0.07-0.10, 95% CI: 0.05-0.14), and cognitive performance (β = 0.30, 95% CI: 0.24-0.36). Device-measured PA was potentially associated with one sarcopenia-related feature (β = 0.14, 95% CI: 0.03-0.25).

CONCLUSIONS

Our findings support the potential causality of educational attainment on biological, phenotypic, and functional aging outcomes, of occupational attainment on phenotypic and functional aging-related outcomes, and of PA on phenotypic aging-related outcomes.

Causal association between mental disorders and cerebrovascular diseases: Evidence from Mendelian randomization study

BACKGROUND AND OBJECTIVE

Observational studies have suggested that mental disorders and cerebrovascular diseases (CVDs) may be risk factors for each other, but genetic evidence of a causal relationship is still lacking. We used Mendelian randomization (MR) studies to explore the causal relationship between mental disorders and CVDs from the genetic perspective.

METHODS

To investigate the causal association between major depressive disorder (MDD), anxiety, attention deficit/hyperactivity disorder (ADHD), bipolar disorder and schizophrenia five kinds of mental disorders and CVDs using two-sample two-way MR analysis based on publicly available genome-wide association study (GWAS) data. We used as instrumental variables (IVs) single-nucleotide polymorphisms (SNPs) that were strongly associated with mental disorders and CVDs. IVW method was used as the main analysis method, and MR-IVW, MR-Egger methods, MR-PRESSO test, leave-one-out analysis and funnel plot were used for sensitivity analysis. We further conducted a meta-analysis to summarize the currently available MR analyses.

RESULTS

The results of forward MR study showed that there was a significant causal relationship between ADHD and AS (any stroke) (p(AS) = 0.001, OR (95%CI) =1.118 (1.047-1.195)), any ischemic stroke (AIS) (p(AIS) = 0.004, OR (95%CI) =1.118(1.035-1.206)) and large artery stroke (LAS) (p(LAS) = 0.026, OR (95%CI): 1.206(1.023-1.422)). No heterogeneity, pleiotropy and outliers were found in sensitivity analysis. The reverse MR study showed that IA (intracranial aneurysm) (p(IA) = 0.033, OR (95%CI) = 1.123(1.009-1.249)) and UIA (unruptured intracranial aneurysm) (p(UIA) = 0.015, OR (95%CI) =1.040(1.008-1.074)) were risk factors for schizophrenia. Sensitivity analysis showed no pleiotropy, but there was heterogeneity. After excluding outliers, MR analysis showed that IA and UIA were still risk factors for schizophrenia. Our meta-analyses found statistical significance in causal relationships between ADHD and LAS (OR (95%CI) =1.18 (1.06-1.32), p = 0.003), IA and schizophrenia (OR (95%CI) =1.05 (1.02-1.08), p = 0.002) and UIA and schizophrenia (OR (95%CI) =1.03 (1.01-1.06), p = 0.010).

CONCLUSION

The MR study and meta-analysis suggest that genetically predicted ADHD is a risk factor for LAS, and IA and UIA increase the risk of schizophrenia. The result has implications for the development of feasible prevention strategies in the future.

Association of anxiety disorder, depression, and bipolar disorder with autoimmune thyroiditis: A bidirectional two-sample mendelian randomized study

BACKGROUND

Anxiety disorder, depression, and bipolar disorder are common psychiatric disorders, and their association with autoimmune thyroiditis (AIT) has been of great interest. This study aimed to investigate the potential causal relationship between these psychiatric disorders and AIT.

METHODS

We used publicly available summary statistics from large-scale genome-wide association studies to select, quality control and cluster genetic variant loci associated with anxiety disorder, depression, bipolar disorder and AIT as instrumental variables (IVs). The Mendelian randomization (MR) study mainly used inverse variance weighting (IVW) combined with MR-egger regression and weighted median estimation (WME) to estimate bidirectional causality between mental disorders and AIT. In addition, we conducted heterogeneity and multivariate tests to verify the validity of IVW.

RESULTS

Two-sample bidirectional MR analysis revealed a positive causal link between depression and AIT. The forward MR analysis of IVW (OR 1.614, 95 % CI 1.104-2.358, P = 0.013) and WME (OR 2.314, 95 % CI 1.315-4.074, P = 0.004) demonstrated thatdepression potentially elevate the risk of AIT development, while, our investigation did not uncover a causal relationship between anxiety disorder, bipolar disorder and AIT. The results of reverse MR analysis showed that there was no significant causal relationship between AIT and anxiety disorder, depression, and bipolar disorder (P > 0.05).

CONCLUSIONS

The results of the forward MR analysis suggest a positive association between depression, and AIT risk, while indicating no support for a causal link between anxiety disorder or bipolar disorder and AIT risk based on the current data. Subsequent studies will be essential for elucidating the biological mechanisms and potential confounders underlying these associations.

Exploring pleiotropy in Mendelian randomisation analyses: What are genetic variants associated with 'cigarette smoking initiation' really capturing?

Genetic variants used as instruments for exposures in Mendelian randomisation (MR) analyses may have horizontal pleiotropic effects (i.e., influence outcomes via pathways other than through the exposure), which can undermine the validity of results. We examined the extent of this using smoking behaviours as an example. We first ran a phenome-wide association study in UK Biobank, using a smoking initiation genetic instrument. From the most strongly associated phenotypes, we selected those we considered could either plausibly or not plausibly be caused by smoking. We examined associations between genetic instruments for smoking initiation, smoking heaviness and lifetime smoking and these phenotypes in UK Biobank and the Avon Longitudinal Study of Parents and Children (ALSPAC). We conducted negative control analyses among never smokers, including children. We found evidence that smoking-related genetic instruments were associated with phenotypes not plausibly caused by smoking in UK Biobank and (to a lesser extent) ALSPAC. We observed associations with phenotypes among never smokers. Our results demonstrate that smoking-related genetic risk scores are associated with unexpected phenotypes that are less plausibly downstream of smoking. This may reflect horizontal pleiotropy in these genetic risk scores, and we would encourage researchers to exercise caution this when using these and genetic risk scores for other complex behavioural exposures. We outline approaches that could be taken to consider this and overcome issues caused by potential horizontal pleiotropy, for example, in genetically informed causal inference analyses (e.g., MR) it is important to consider negative control outcomes and triangulation approaches, to avoid arriving at incorrect conclusions.

Causal influences of testosterone on brain structure change rate: A sex-stratified Mendelian randomization study

The impact of testosterone levels on changes in brain structure has been reported. However, it is still unclear which specific brain region could be affected. This study approached Mendelian randomization method to reveal the causal relationship between testosterone levels and the rate of longitudinal structural changes in the brain. The testosterone-related GWAS data were determined from 425,097 European participants. The GWAS data on the rate of longitudinal structural changes in the brain came from the ENIGMA consortium, which included 15,640 all-age participants from 40 longitudinal cohorts. The inverse variance weighted was considered as the main estimate, MR Egger and weighted median methods were used to supplement IVW. A positive correlation was found between total testosterone levels and bioavailable testosterone levels in women and age-independent longitudinal changes in cerebral WM and surface area. The sex hormone-binding globulin levels were found a negative correlation with age-dependent longitudinal structural changes of cortical GM in men. Additionally, we also found that the bioavailable testosterone level in males was negatively associated with the quadratic age-dependent longitudinal change rate in the globus pallidum. We also found estradiol levels and sex hormone-binding globulin levels were negatively associated with the quadratic age-dependent longitudinal change rate of total brain in men. Moreover, we found a positive correlation between total testosterone levels and linear age-dependent longitudinal changes in the hippocampus in both males and females. The testosterone levels in different genders may have varying degrees of causal effects on the structural changes of brain regions. These findings provide evidence for the influence of the brain glandular axis on brain structure, particularly during female brain development.

Causality Between ADHD, ASD, and CVDs: A Two-Step, Two-Sample Mendelian Randomization Investigation

BACKGROUND

While observational studies have established a connection between attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and heightened risk for cardiovascular diseases (CVD), the causal relationships are not well-defined. This study is designed to examine the causality between ASD, ADHD, and CVD risk as well as investigate the mediating factors through which ADHD and ASD influence CVD.

METHODS AND RESULTS

Leveraging two-sample Mendelian randomization (MR) approaches and large scale GWAS summary stats, we examined underlying causal links between ASD and ADHD and the risk of CVDs. The analysis indicated that ADHD was related to an increased likelihood of developing coronary heart disease (OR [95% CI] 1.12 [1.03, 1.21], p = .008), heart failure (OR [95% CI] 1.14 [1.07, 1.22], p = 1.45 × 10-4), and large-artery stroke (OR [95% CI] 1.35 [1.09, 1.66], p = .005). In parallel, ASD showed a correlation with a greater atrial fibrillation risk (OR [95% CI] 1.09 [1.03, 1.16], p = .005] and heart failure (OR [95% CI] 1.11 [1.04, 1.19], p = .004). Additionally, we explored the mediating role of CVD risk factors through two-step MR and multivariable MR, highlighting the possible role of smoking, prescription opioid use, triglycerides, education, income, Townsend deprivation index, and obesity in the causal association of ADHD, ASD, on CVDs.

CONCLUSION

This MR study highlights the necessity for rigorous cardiovascular surveillance and interventions to decrease adverse cardiovascular events in people with ADHD or ASD by preventing identified mediating risk factors.

Exploring Putative Causal Associations between Diet and Periodontal Disease Susceptibility

INTRODUCTION

Dietary factors may play an important role in periodontal health. However, current evidence from observational studies remains inconclusive.

OBJECTIVE

This study aimed to investigate the causal relationships between dietary exposures and periodontal disease risks using Mendelian randomization analysis.

METHODS

Large-scale genome-wide association study summary statistics for 20 dietary factors were obtained from the MRC-IEU consortium. Multivariable and univariable 2-sample Mendelian randomization analyses were performed to assess the causal effects of each dietary exposure on 6 periodontal outcomes, including gingivitis and periodontitis.

RESULTS

Genetically predicted higher dried fruit intake was significantly associated with reduced risks of acute gingivitis (odds ratio [OR]: 0.02; 95% confidence interval [CI]: 0.00-0.42; P = 0.01) and bleeding gums (OR: 0.96; 95% CI: 0.93-0.99; P = 0.01). Higher fresh fruit and water intake showed protective effects against chronic gingivitis (OR: 0.18; 95% CI: 0.04-0.91; P = 0.04 and OR: 0.15; 95% CI: 0.04-0.53; P = 0.00) and bleeding gums (OR: 0.95; 95% CI: 0.92-0.981; P = 0.00 and OR: 0.98; 95% CI: 0.96-0.99; P = 0.02). Alcohol intake frequency and processed meat intake were risk factors for bleeding gums (OR: 1.01; 95% CI: 1.00-1.02; P = 0.01 and OR: 1.05; 95% CI: 1.01-1.08; P = 0.00) and painful gums (OR: 1.01; 95% CI: 1.00-1.01; P = 0.00 and OR: 1.02; 95% CI: 1.01-1.03; P = 0.00). Most of the causal relationships between genetic predisposition to the specified dietary factors and periodontal diseases remained statistically significant (P < 0.05) after adjusting for genetic risks associated with dentures, smoking, and type 2 diabetes in multivariable Mendelian randomization models.

CONCLUSIONS

The findings suggest potential protective effects of higher fruit and water intake against gingivitis and other periodontal problems, while alcohol and processed meat intake may increase the risks of periodontal disease. Our study provides preliminary causal evidence on the effects of diet on periodontal health and could inform prevention strategies targeting dietary habits to improve oral health.

KNOWLEDGE TRANSFER STATEMENT

This study suggests that fruit and water intake may protect against periodontal disease, while alcohol and processed meats increase risk, informing dietary guidelines to improve oral health.

Causal role of immune cells in asthma: a Mendelian randomization study

BACKGROUND

Immune cells may have a significant role in the pathophysiology of asthma, according to increasing evidence, although it is yet unclear how immune cells cause asthma. Therefore, we aimed to use Mendelian randomization (MR) methods to investigate this causal relationship.

METHODS

This study explored the causal effects between immune cells and asthma using a two-sample MR technique. Using publicly available genetic data, the causal connection between asthma risk and 731 immune cell phenotypes was investigated. Sensitivity analysis guaranteed the results' stability. To further evaluate the existence of reverse causality, we employed reverse MR analysis.

RESULTS

According to the inverse-variance weighted (IVW) method, five immune cell phenotypes were found to be statistically significantly associated with asthma risk (p < 0.001). Among them, TCRgd %T cell (OR = 0.968, 95%CI = 0.951 - 0.986), TCRgd %lymphocyte (OR = 0.978, 95%CI = 0.965 - 0.991), HLA DR + NK AC (OR = 0.966, 95% CI = 0.947 - 0.986) and CD3 on CD4 Treg (OR = 0.956, 95%CI= 0.931 - 0.981), four phenotypes that resulted in a decreased risk of asthma. CD25 on transitional (OR = 1.033, 95%CI = 1.014 - 1.052) resulted in an increased risk of asthma. Reverse MR analysis revealed that asthma increases HLA DR + NK AC levels (p < 0.05).

CONCLUSION

The results of MR analysis showed a causal relationship between immune cell phenotype and asthma risk, which provides a direction for future asthma treatment.

Exploring and Accounting for Genetically Driven Effect Heterogeneity in Mendelian Randomization

Mendelian randomization (MR) is a framework to estimate the causal effect of a modifiable health exposure, drug target or pharmaceutical intervention on a downstream outcome by using genetic variants as instrumental variables. A crucial assumption allowing estimation of the average causal effect in MR, termed homogeneity, is that the causal effect does not vary across levels of any instrument used in the analysis. In contrast, the science of pharmacogenetics seeks to actively uncover and exploit genetically driven effect heterogeneity for the purposes of precision medicine. In this study, we consider a recently proposed method for performing pharmacogenetic analysis on observational data-the Triangulation WIthin a STudy (TWIST) framework-and explore how it can be combined with traditional MR approaches to properly characterise average causal effects and genetically driven effect heterogeneity. We propose two new methods which not only estimate the genetically driven effect heterogeneity but also enable the estimation of a causal effect in the genetic group with and without the risk allele separately. Both methods utilise homogeneity-respecting and homogeneity-violating genetic variants and rely on a different set of assumptions. Using data from the ALSPAC study, we apply our new methods to estimate the causal effect of smoking before and during pregnancy on offspring birth weight in mothers whose genetics mean they find it (relatively) easier or harder to quit smoking.

Systemic inflammatory regulators are associated with two common types of neuropathic pain: A bidirectional Mendelian randomization study

BACKGROUND

Currently, there is limited and inconsistent evidence regarding the causal relationship between systemic inflammatory regulators and two common types of neuropathic pain, namely, postherpetic neuralgia (PHN) and trigeminal neuralgia (TN). This study employed a Mendelian randomization (MR) approach to investigate the causal relationship between systemic inflammatory regulators and these two common neuropathic pain conditions.

METHODS

In this study, 41 single-nucleotide polymorphisms (SNPs) associated with PHN and TN were selected as instrumental variables (IVs) representing systemic inflammatory regulators. Genetic associations of systemic inflammatory regulators were derived from recent genome-wide association studies (GWAS) on the human proteome and cytokines. Genetic data related to PHN and TN were obtained from the FinnGen. The primary analytical method utilized inverse variance weighting (IVW) and various sensitivity analyses.

RESULTS

Prior to applying the false discovery rate (FDR) correction, our bidirectional MR analysis revealed that increased levels of IFNγ (OR: 0.46, 95% CI: 0.24-0.87, PIVW: 0.016) and MCP3 (OR: 0.52, 95% CI: 0.35-0.77, PIVW: 0.001) were associated with a reduced risk of PHN, and increased levels of IL-16 (OR: 0.81, 95% CI: 0.67-0.98, PIVW: 0.026) were causally associated with a reduced risk of TN. In discussing the impact of PHN and TN on systemic inflammatory regulator levels, we observed the following findings: The BETA for CTACK was -0.07 (95% CI: -0.13 to -0.01, PIVW: 0.015), the BETA for FGFBasic was -0.04 (95% CI: -0.08 to -0.01, PIVW: 0.020), and the BETA for IL-17 was -0.04 (95% CI: -0.08 to -0.01, PIVW: 0.019). These results indicate that patients with PHN tend to have lower levels of CTACK, FGFBasic, and IL-17. Conversely, the BETA for IFNγ was -0.09 (95% CI: -0.18 to 0.00, PIVW: 0.046), suggesting that patients with TN tend to have lower levels of IFN γ. However, after FDR correction, only the association between MCP3 and PHN remained statistically significant (PFDR: 0.044).

CONCLUSION

This study found that certain systemic inflammatory regulators are associated with PHN and TN to some extent. However, further research is needed to explore the specific mechanisms underlying these connections.

Causal Relationship Between Inflammatory Cytokines and Pancreatitis Risk

The causal relationship between inflammatory factors and acute pancreatitis (AP), chronic pancreatitis (CP), alcohol-induced acute pancreatitis (AAP), and alcohol-induced chronic pancreatitis (ACP) remains unclear. We aimed to examine the casual relationship between inflammatory factors and various forms of pancreatitis, namely, AP, CP, AAP, and ACP. We employed a two-sample Mendelian randomization (MR) analysis to investigate the causal relationship between 91 inflammatory factors and 41 inflammatory factors with respect to pancreatitis. The primary analysis involved the use of the inverse variance weighting (IVW). MR-Egger intercept test, Cochran's Q test, MR-PRESSO test, and Leave-One-Out analysis were used to assess the robustness of our findings. IVW analysis revealed evidence of association between 24 inflammatory cytokines and pancreatitis. Specifically, six cytokines were associated with AP, eight cytokines were associated with CP, three cytokines were associated with AAP, and seven cytokines were associated with ACP. The most significant associations were observed with β nerve growth factor (odds ratio [95% confidence interval]: 6.05 [1.59, 23.01]) and interleukin-4 [IL-4; 2.56 (0.91, 7.16)] in AAP, as well as interleukin-2 receiver subunit beta and IL-4 in ACP. Our findings suggest that certain inflammatory cytokines may have a significant role in the development of pancreatitis.

Causal relationship between cheese intake and risk of gastroesophageal reflux disease and Barrett's esophagus: findings from multivariable mendelian randomization and mediation analysis

OBJECTIVE

Previous studies have indicated a potential correlation between cheese intake and risk of various diseases. However, establishing a causal relationship is challenging. To address this, we employed Mendelian randomization (MR) to simulate randomized trial groups and to investigate whether there is a causal link between cheese intake and the risk of gastroesophageal reflux disease (GERD) and Barrett's esophagus.

METHODS

We conducted a multivariable MR analysis using individual-level data on GERD and Barrett's esophagus from the published datasets. Univariable and multivariable MR investigations were carried out to explore and substantiate the causal association between genetically predicted cheese intake and esophageal diseases. Additionally, a network MR analysis was executed to identify potential intermediate variables.

RESULTS

Based on the primary causal effects model using MR analyses with the inverse-variance weighted (IVW) method, the genetically predicted that cheese intake demonstrated a protective factor of GERD (OR = 0.356; 95% CI 0.256-0.495; P = 8.22E-10) and Barrett's esophagus (OR = 0.223; 95% CI 0.114-0.437; P = 1.19E-5). These effects remained consistent after adjusting for potential confounders such as tobacco smoking (GERD: OR = 0.440; 95% CI 0.347 - 0.558; P = 1.17E-11; Barrett's esophagus: OR = 0.263; 95% CI 0.160 - 0.432; P = 1.33E-7) and BMI (GERD: OR = 0.515; 95% CI 0.424 - 0.626; P = 2.49E-11; Barrett's esophagus: OR = 0.402; 95% CI 0.243 - 0.664; P = 3.72E-4). Furthermore, the network MR showed that BMI mediated 28.10% and 27.50% of the causal effect of cheese intake on GERD and Barrett's esophagus, respectively, with statistically significant mediation effects.

CONCLUSION

The multivariable MR analysis conducted in this study revealed a reverse causal relationship between cheese intake and GERD and Barrett's esophagus. Furthermore, BMI was potential mediating factor of the cheese intake effects on GERD and Barrett's esophagus. This finding provides causal evidence for the potential protective role of cheese intake in the prevention of esophageal diseases. The mediating effect of BMI suggests that dietary interventions combined with weight management may help reduce the risk of these diseases.

The causal relationship of cigarette smoking to metabolic disease risk and the possible mediating role of gut microbiota

BACKGROUND

Cigarette smoking is a leading cause of preventable death worldwide, with its associated diseases and conditions. Emerging evidence suggests that cigarette smoking contributes to a range of pathological metabolic injuries, including diabetes and nonalcoholic fatty liver disease (NAFLD). The impact of gut microbiota on metabolic health and diseases has been observed, but the causality remains uncertain.

OBJECTIVE

To confirm the causal relationship between cigarette smoking and metabolic diseases, and to investigate the possible mediating effect of gut microbiota on these connections.

METHODS

The relationships among cigarette smoking, metabolic diseases, and the gut microbiome were analyzed by Univariate Mendelian randomization (UVMR). Furthermore, to mitigate the impact of confounding factors, adjusted models were conducted via the multivariate Mendelian randomization (MVMR) method, aiming to improve the accuracy of prediction. Ultimately, the study evaluated the effect of the intermediary factor, gut microbiome, on the relationship between cigarette smoke and metabolic diseases.

RESULTS

The phenomenon that a causal relationship between cigarette smoke (249752 individuals) and gut microbiota (7738 individuals), diabetes (406831 individuals), NAFLD (377998 individuals), hypercholesterolaemia (463010 individuals), and obesity (463010 individuals) was observed using UVMR. In the MVMR model, the genetic connection between cigarette smoking, gut microbiota, and type 2 diabetes remained significant. Of note, paraprevotella_clara served an important mediating role in the type 2 diabetes associated with cigarette smoke.

CONCLUSION

This work offered genetic evidence linking cigarette smoke to metabolic diseases, suggesting that the gut microbiota, particularly paraprevotella_clara, might be a crucial mediator in the development of type 2 diabetes caused by cigarette smoke. Our future studies should consider conducting other ethnic groups MR analyses, particularly with larger sample sizes. Still, more in vivo and in vitro work should be carried out to validate the precise effect and molecular mechanisms of the gut microbiome.

Investigating Causal Associations of Diet Compositions with the Risk of Lung Cancer

OBJECTIVE

This study aimed to investigate the causal relationship between diet compositions and lung cancer (LC) risk.

METHODS

A two-sample Mendelian randomization (MR) analysis was performed to assess the causal relationship between diet and LC risk, including three LC subtypes. Instrumental variables (IVs) for three diet compositions were selected from genome-wide association studies (GWAS). Summary statistics for LC and its subtypes came from the largest meta-analysis. The inverse-variance weighted (IVW) method was used as the main MR analysis, with sensitivity analyses to ensure result robustness. Then, we conducted an observational study using data from National Health and Nutrition Examination Survey (NHANES) to verify the relationship.

RESULTS

Our results showed significant evidence that fat intake was correlated with the lower risk of lung adenocarcinoma. There were also suggestive correlations between fat intake and overall LC. However, no significant associations were found between other macronutrients and LC risk. NHANES data further showed that higher polyunsaturated fatty acid (PUFA) intake was linked to better outcomes in LC patients.

CONCLUSION

PUFA intake may have a protective effect against LC. Adjusting dietary proportions could potentially help in the primary prevention of LC.

Genetic correlation and mendelian randomization reveal the impact of sleep traits on urolithiasis risk

Urolithiasis is a common and recurrent condition in the urological spectrum. Despite various proposed mechanisms, the causal relationship between sleep traits and the risk of urolithiasis remains unclear. We used publicly available genome-wide association study (GWAS) summary data from the UK Biobank and FinnGen to perform a two-sample Mendelian randomization (MR) analysis and genetic correlation analysis, evaluating the causal relationship and genetic correlation between sleep traits (chronotype, getting up in the morning, sleep duration, nap during the day, and insomnia) and urolithiasis (calculus of the kidney and ureter, and calculus of the lower urinary tract). Additionally, multivariable MR (MVMR) analysis adjusted for body mass index (BMI) and other sleep characteristics was conducted to assess the direct impact of sleep traits on the risk of urinary tract stones. The LD score regression (LDSC) analysis indicated a genetic correlation between insomnia and upper urinary tract stones (rg = 0.082, P = 0.017, Adjusted P = 0.085), but no significant genetic correlation was found for other sleep traits. Our results indicated no causal relationship between sleep traits and upper urinary tract stones. However, insomnia was significantly associated with a higher risk of lower urinary tract stones (IVW [inverse variance weighted] OR [odds ratio] = 5.91, 95% CI [confidence interval] 1.52-22.98, P = 0.010, Adjusted P = 0.030), while early rising exhibited a protective effect (IVW OR = 0.29, 95% CI 0.11-0.76, P = 0.012, Adjusted P = 0.030). In the MVMR analysis, insomnia consistently showed a similar trend, whereas daytime napping significantly reduced the risk of lower urinary tract stones (OR = 0.28, 95% CI 0.12-0.65, P = 0.003). This study provides MR-based evidence suggesting that insomnia may increase the risk of lower urinary tract stones, while daytime napping may reduce this risk. No causal relationship was found between sleep characteristics and upper urinary tract stones.

A Modified Debiased Inverse-Variance Weighted Estimator in Two-Sample Summary-Data Mendelian Randomization

Mendelian randomization uses genetic variants as instrumental variables to estimate the causal effect of exposure on outcome from observational data. A common challenge in Mendelian randomization is that many genetic variants are only modestly or even weakly associated with the exposure of interest, a setting known as many weak instruments. Conventional methods, such as the popular inverse-variance weighted (IVW) estimator, could be heavily biased toward zero when the instrument strength is weak. To address this issue, the debiased IVW (dIVW) estimator and the penalized IVW (pIVW) estimator, which are shown to be robust to many weak instruments, were recently proposed. However, we find that the dIVW estimator tends to produce an exaggerated estimate of the causal effect, especially when the effective sample size is small. Although the pIVW estimator has better statistical properties, it is slightly more complex, and the idea behind this method is also a bit less intuitive. Therefore, we propose a modified debiased IVW (mdIVW) estimator that directly multiplies a shrinkage factor with the original dIVW estimator. After this simple modification, we prove that the mdIVW estimator not only has second-order bias with respect to the effective sample size, but also has smaller variance and mean squared error than the preceding two estimators. We then extend the proposed method to account for the presence of instrumental variable selection and balanced horizontal pleiotropy. We demonstrate the improvement of the mdIVW estimator over the competing ones through extensive simulation studies and real data analysis.

Causal relationship between genetically determined plasma metabolites and stroke: A two sample Mendelian randomization study

INTRODUCTION

This study investigates the causal relationship between plasma metabolites and stroke.

METHOD

The primary analytical approach employed was the inverse variance weighted (IVW) method, complemented by the weighted median (WM) and MR Egger methods for Additionally, validation of the identified plasma metabolites was performed using the Steiger test and LD linkage disequilibrium score. Furthermore, the main results were confirmed through data from the UK Biobank.

RESULT

The IVW analysis revealed the most notable negative association found in X-17335 levels (OR [95 % CI]: 0.82 [0.72, 0.94]). On the other hand, the strongest positive effect was seen in the 5'-homophase (AMP) to phase ratio (OR [95 % CI]: 1.17 [1.03, 1.32]). Moving on to the validation dataset, the most significant positive effect was observed in the 13 HODE+9-HODE levels (OR [95 % CI]: 0.996 [0.993, 0.999]), whereas the most significant negative effect was seen in the Dihydroxide levels (OR [95 % CI]: 1.004 [1.00, 1.007]). Notably, Alpha ketoglutarate levels exhibited strong causal effects in both datasets (OR 0.908 [0.841, 0.981], p = 0.0144). Enrichment analysis highlighted the association of Alpha ketoglutarate levels with five plasma metabolites in metabolic pathways relevant to stroke, specifically Arginine biosynthesis, Butanoate metabolism, Citrate cycle (TCA cycle), Alanine, aspartate, and glutamate metabolism, and Lipid acid metabolism, all linked to oxoglutaric acid.

CONCLUSION

The discovery dataset showed the most significant positive effect of the 5'-homophase (AMP) to phase ratio, while the validation dataset revealed the most significant positive effect of the 13 HODE+9-HODE levels. Additionally, alpha ketoglutarate may offer a potential protective effect on stroke by influencing five metabolic pathways that intersect with Oxoglutaric acid during the progression of the condition.

Relationship between hypothyroidism and chronic kidney disease: Results from the National Health and Nutrition Examination Survey 2007 to 2012 and Mendelian randomization study

Chronic kidney disease (CKD) and hypothyroidism are prevalent chronic conditions with a generally believed correlation between them. However, large-scale population studies and investigations into causation are lacking. This study analyzed CKD and thyroid function data from the National Health and Nutrition Examination Survey database spanning 2007 to 2012 using multiple regression analyses to examine the correlation between CKD and hypothyroidism. Bidirectional Mendelian randomization analysis was employed to investigate the causal association between the two conditions. As CKD stages deteriorated, there was a significant decrease in total triiodothyronine (TT3) and free triiodothyronine (P < .05). However, no significant decrease was observed in total thyroxine and free thyroxine. Notably, there was a significant increase in thyroid-stimulating hormone levels (P < .05). However, no significant changes were observed in thyroglobulin, thyroglobulin antibody, and thyroid peroxidase antibody levels. A causal relationship between CKD and reduced thyroid function was observed (odds ratio [OR] = 1.0041, 95% confidence interval [CI]: 1.0007-1.0075, P = .0186). Conversely, reverse causality was not statistically significant (OR = 2.540, 95%CI: 0.8680-4.8603, P = .1014). As CKD progressed, the risk of hypothyroidism increased. A causal correlation was observed between CKD and reduced thyroid function. Chronic kidney disease (CKD) and hypothyroidism are prevalent chronic conditions with a generally believed correlation between them. There is no large-scale population studies and the causation relationship between CKD and hypothyroidism are lacking. The finding of the causal relationship between CKD and hypothyroidism may be beneficial to the prevention of the disease and the prognosis of the patients.

Genetic prediction of serum micronutrient levels and the risk of frailty: Evidence from a Mendelian randomization study

Although observational studies have revealed a link between frailty and serum micronutrient levels, it remains unclear whether these 2 states are directly connected. Thus, Mendelian randomization (MR) was used to investigate the causal relationship between frailty and blood micronutrient levels. Summary-level data for 15 blood micronutrients (copper, selenium, zinc, calcium, iron, magnesium, potassium, folate, carotene, vitamin A, vitamin B6, vitamin B12, vitamin C, vitamin D, and vitamin E) were obtained from people of European ancestry from the Integrative Epidemiology Unit. Single nucleotide polymorphisms associated with the frailty index were extracted from a published meta-analysis study in the UK Biobank and Swedish TwinGene. We used the inverse variance weighted (IVW) method for the primary analysis. We employed pleiotropy residual sum and outlier (MR-PRESSO) tests, MR-Egger intercepts, Cochran Q tests, and leave-one-out analysis to assess causality validity and robustness. Reverse MR analysis was used to determine reverse causation. The IVW results revealed that vitamin D (odds ratio [OR] = 1.096; 95% confidence interval [CI]: 1.019-1.178; P = .014) increased the likelihood of a high risk of frailty, whereas the frailty index had a protective effect on selenium (OR = 0.622; 95% CI: 0.396-0.977; P = .039), carotene (OR = 0.916; 95% CI: 0.858-0.979; P = .009), vitamin C (OR = 0.895; 95% CI: 0.837-0.957; P = .001), iron (OR = 0.921; 95% CI: 0.859-0.988; P = .022), and vitamin E (OR = 0.907; 95% CI: 0.847-0.971; P = .005). The reverse IVW analysis revealed no significant correlation between micronutrient levels and frailty indices. The study revealed causal links between vitamin D and the risk of frailty. Notably, our findings highlight the necessity of adjuvant vitamin D in frailty management.

Modifiable lifestyle factors and risk of intracranial aneurysm: A univariate and multivariate Mendelian randomisation study

The aim of this study was to assess the potential causal relationship between lifestyle factors and intracranial aneurysms (IAs) using a two-sample Mendelian randomization (MR) approach. The study used a pooled dataset from a genome-wide association study that covered information on 24 lifestyle factors, intracranial aneurysm cases, subarachnoid hemorrhage, and unruptured aneurysms. Five MR methods were applied for analysis by selecting single nucleotide polymorphisms as instrumental variables, with the inverse variance weighting method as the main method. To ensure the stability of the results, horizontal multiple validity tests, sensitivity analyses, and inverse MR were performed, and genetically determined exposure factors were adjusted by multivariate MR. Several lifestyle factors were found to have a significant genetic causal effect on the occurrence and development of intracranial aneurysms. For example, lamb intake, smoking initiation, number of cigarettes smoked per day, length of television viewing, and fatigue were identified as genetic risk factors and strongly associated with aneurysm rupture, whereas red wine intake showed some genetic protection against intracranial aneurysms and similarly affected aneurysm rupture. Sensitivity analyses and inverse MR verified the robustness of these results. After adjusting for exposure factors, multivariate MR confirmed daily smoking and smoking initiation as risk factors for intracranial aneurysms, unruptured aneurysms, and subarachnoid hemorrhage, whereas red wine intake was a genetically protective factor against intracranial aneurysms and subarachnoid hemorrhage. This MR analysis revealed a genetic causal link between specific lifestyle factors and intracranial aneurysms, emphasizing the need for further studies to confirm these findings and explore their mechanisms.

Mendelian randomization analyses support causal relationships between HPV infection and colorectal cancer

BACKGROUND

Human Papillomavirus (HPV) infections leading to a variety of diseases are a global public health issue.Despite the well-established link between HPV infection and cervical and anogenital cancers, there is ongoing debate regarding the relationship between HPV infection and colorectal cancer (CRC).

METHODS

We evaluated the causal connection between HPV infection and CRC utilizing five Mendelian randomization (MR) methods. Genome-wide association studies (GWAS) datasets for HPV were obtained from the IEU Open GWAS project. A large summary of colorectal adenocarcinoma and colorectal cancer data from the FinnGen database was used as the outcome.

RESULTS

Our analysis revealed a significant association between genetically predicted HPV-16 infection and the risk of paternal colorectal adenocarcinoma (HPV-16: OR 1.058, 95% CI 1.013-1.102; p = 0.011), as well as CRC (HPV-16: OR 1.045, 95% CI 1.005-1.085; p = 0.025).

CONCLUSION

These findings provide compelling evidence for a causal effect of HPV infection on the development of CRC. Further investigations into the underlying mechanisms and elucidation of this association are necessary to identify viable interventions for the prevention and treatment of HPV-associated CRC.

IL-20RA is Associated with the Risk of Diabetic Microangiopathy: A Bidirectional Mendelian Randomization Analysis and Clinical Validation

Objective

Studies have demonstrated a link between chronic inflammatory responses and diabetic microangiopathy, which include diabetic nephropathy, diabetic retinopathy, and diabetic neuropathy. However, it remains unclear whether there is a causal association between circulating inflammatory cytokines and the development of diabetic microvascular complications. This study aimed to investigate whether altered genetically predicted concentrations of circulating inflammatory cytokines were associated with the development of diabetic microvascular complications using two-sample Mendelian randomization (MR) analysis and clinical validation.

Methods

Pooled data on diabetic nephropathy, diabetic retinopathy, diabetic neuropathy, and 91 circulating inflammatory cytokines were obtained from publicly available databases. The analysis was conducted mainly using the inverse variance weighting (IVW) method and the results were assessed based on the odds ratio (OR) and 95% confidence interval (CI). In addition, the stability and reliability of the results were verified using the leave-one-out method, heterogeneity tests, and horizontal pleiotropy. Finally, ELISA and RT-qPCR were utilized to assess the expression of relevant inflammatory cytokines associated with diabetic microvascular complications.

Results

Mendelian randomization analysis identified a total of 9 circulating inflammatory cytokines that exhibit causal associations with the diabetic microangiopathy, with IL-20RA being a common risk factor for all three conditions. Clinical studies have found elevated plasma IL-20RA concentrations in patients with diabetic peripheral neuropathy, and RT-qPCR testing of peripheral blood mononuclear cells revealed significantly higher IL-20RA mRNA expression in patients with diabetic peripheral neuropathy as compared to normal individuals.

Conclusion

This study highlights the potential role of specific inflammatory cytokines in the development of diabetic microangiopathy (diabetic nephropathy, diabetic retinopathy and diabetic neuropathy). Additionally, IL-20RA emerges as a potential common risk factor for three diabetic microvascular complications. These findings may provide novel insights into early prevention and new therapeutic strategies for diabetic microvascular complications.

Investigating the Gene Relation Between Cervical Spondylosis and Depression: Bidirectional Mendelian Randomization Study

Background

Previous observational studies have suggested a potential link between depression and cervical spondylosis (CS). While it is known that depression and CS can coexist, the specific relationship between them is not fully understood. We hypothesize that there may be connections between the two conditions, but the independent causal relationship of depression as a risk factor for CS, remains uncertain. This particular study has important implications for the future clinical treatment of depression and cervical spondylosis because Mendelian randomization has not been widely used in this field. We obtained valuable results through big data analysis and have guiding significance for future research.

Methods

We conducted a two-sample Mendelian randomization (MR) study using data from genome-wide association studies to investigate the causal relationship between depression and CS in individuals of European ancestry. Additionally, we examined the impact of CS on susceptibility to depression using large population-level genetic data (number of depression SNPs: 9,761,853; number of CS SNPs: 9,851,867). The primary approach for data analysis was the inverse-variance weighted (IVW) method to estimate potential causal effects. Furthermore, we performed sensitivity analyses utilizing methods such as Manhattan plot (CMplot), linkage disequilibrium (LD), F-filtering, removal of phenoscanner, MR-Egger, weighted median, MR-PRESSO simple mode weighted mode MR pleiotropy test MR heterogeneity assessment leave-one-out analysis to ensure result robustness.

Results

Our findings indicated that an elevated likelihood of CS was linked to depression [IVW odds ratio (OR): 1.322, 95% confidence interval (CI): 1.205-1.441, P=0.01243]. There was reciprocal evidence of causation, with the genetic predisposition to depression significantly heightening susceptibility to CS [IVW odds ratio (OR): 1.426, 95% confidence interval (CI): 1.236-1.651, P=0.01775].

Conclusion

This investigation provides genetic support for a bidirectional causal association between depression and CS. Specifically, individuals with depression are at greater risk of developing CS. Addressing depression may serve as an effective approach in mitigating or preventing the burden of CS and vice versa.

Estimating and visualising multivariable Mendelian randomization analyses within a radial framework

BACKGROUND

Mendelian randomization (MR) is a statistical approach using genetic variants as instrumental variables to estimate causal effects of a single exposure on an outcome. Multivariable MR (MVMR) extends this to estimate the direct effect of multiple exposures simulatiously. MR and MVMR can be biased by the presence of pleiotropic genetic variants in the set used as instrumental variables, violating one of the core IV assumptions. Genetic variants that give outlying estimates are often considered to be potentially pleiotropic variants. Radial plots can be used in MR to help identify these variants. Analogous plots for MVMR have so far been unavailable due to the multidimensional nature of the analysis.

METHODS

We propose a radial formulation of MVMR, and an adapted Galbraith radial plot, which allows for the estimated effect of each exposure within an MVMR analysis to be visualised. Radial MVMR additionally includes an option for removal of outlying SNPs which may violate one or more assumptions of MVMR. A RMVMR R package is presented as accompanying software for implementing the methods described.

RESULTS

We demonstrate the effectiveness of the radial MVMR approach through simulations and applied analyses. We highlight how outliers with respect to all exposures can be visualised and removed through Radial MVMR. We present simulations that illustrate how outlier removal decreases the bias in estimated effects under various forms of pleiotropy. We apply Radial MVMR to estimate the effect of lipid fractions on coronary heart disease (CHD). In combination with simulated examples, we highlight how important features of MVMR analyses can be explored using a range of tools incorporated within the RMVMR R package.

CONCLUSIONS

Radial MVMR effectively visualises causal effect estimates, and provides valuable diagnostic information with respect to the underlying assumptions of MVMR.

The impacts of noise and air pollution on breast cancer risk in European and East Asian populations: Insights from genetic evidence

OBJECTIVES

Previous studies have reported associations of noise and air pollution with breast cancer (BC) risk, but the causality remains unclear. This study aimed to explore the effects of noise and air pollution on BC from a genetic perspective.

STUDY DESIGN

Genetic association study.

METHODS

We began our investigation by visualizing the development trends in this field through bibliometric analysis. Subsequently, we conducted Mendelian randomization analyses to assess the effects of noise (daytime and evening) and air pollution (NO2, NOx, PM2.5, PM2.5-10, and PM10) on BC. Genetic variants extracted from genome-wide association studies (GWAS) robustly associated with noise and air pollution were used as instrumental variables. The GWAS data for BC in European and East Asian populations were obtained from the Breast Cancer Association Consortium and the Biobank Japan, respectively.

RESULTS

The effects of noise and air pollution on BC are receiving increasing attention. In the European population, genetically predicted exposure to NO2 (OR: 1.9381; 95% CI: 1.2873-2.9180; P = 0.0015) and PM10 (OR: 1.4187; 95% CI: 1.0880-1.8500; P = 0.0098) were positively associated with overall BC risk. Subtype analyses showed that PM10 was significantly related to the risks of both ER+ (OR: 1.6165; 95% CI: 1.1778-2.2186; P = 0.0030) and ER- (OR: 1.6228; 95% CI: 1.0175-2.5881; P = 0.0421) BC. Additionally, NO2 only increased the risk of ER+ BC (OR: 1.7429; 95% CI: 1.0679-2.8444; P = 0.0262), but not ER- BC. In East Asians, genetically predicted NO2 was positively related to BC risk (OR: 1.1394; 95% CI: 1.0082-1.2877; P = 0.0366).

CONCLUSIONS

Our study gave new evidence from a genetic standpoint underscoring that improving the environmental quality of residential areas is conducive to reducing BC risk.

Causal relationships between depression, emotional changes, and hiatal hernia: A Mendelian randomization analysis

Hiatal hernia (HH) is a common gastrointestinal disorder characterized by the displacement of abdominal contents, particularly the stomach, into the thoracic cavity. This condition is frequently associated with gastroesophageal reflux disease (GERD) and can lead to various symptoms, including chronic cough and respiratory issues. Despite its prevalence, the mechanisms linking psychological factors to HH are not well understood. Observational studies have suggested correlations between mental health issues - such as stress, anxiety, and depression - and gastrointestinal disorders, indicating that emotional states may influence the development of HH. This study aims to clarify the causal relationships between mood swings, depression, and the risk of developing HH using Mendelian randomization (MR), a robust method that utilizes genetic variants as instrumental variables (IVs) to infer causality. Data for this MR analysis were obtained from publicly available genome-wide association studies (GWAS). We employed a bidirectional, 2-sample MR approach, using IVs associated with mood swings, depression, feelings of tension, and feelings of misery as exposures, with HH as the outcome. A reverse MR analysis was also conducted, treating HH as the exposure and the aforementioned emotional states as outcomes. The primary analytical method used was inverse variance weighting (IVW), supplemented by sensitivity analyses, including MR-Egger and weighted median methods. Our analysis revealed significant associations: mood swings (OR = 1.014; 95% CI = 1.001-1.027; P = .032), depression (OR = 1.019; 95% CI = 1.006-1.033; P = .003), feelings of tension (OR = 1.012; 95% CI = 1.004-1.020; P = .001), and feelings of misery (OR = 1.007; 95% CI = 1.003-1.010; P = .0001) significantly increased the risk of HH. Importantly, reverse MR analysis indicated no causal influence of HH on these emotional states. This study provides evidence that mood swings, depression, feelings of tension, and feelings of misery are significant risk factors for developing HH. These findings highlight the need to address psychological factors in the clinical management and prevention strategies for HH, potentially improving patient outcomes.

Unveiling the mystery: Investigating the debate surrounding mitochondrial DNA copy number and Sjögren syndrome using Mendelian randomization analysis

Numerous studies have investigated the relationship between mitochondrial DNA (mtDNA) copy number and Sjögren syndrome (SS). However, the conclusions remain inconclusive, with conflicting findings. The genome-wide association study summary statistics for mtDNA copy number were obtained from 2 sources: a cohort of 465,809 White individuals from the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium and the UK Biobank, and a dataset of 395,718 UK Biobank participants. Additionally, we obtained 2 sets of genome-wide association study summary statistics for SS through datasets from FinnGen and the UK Biobank, involving a total of 809,836 participants. Furthermore, we conducted a two-sample bidirectional Mendelian randomization analysis, primarily utilizing the inverse variance weighted method, complemented by 4 other validation methods, to explore the association between mtDNA copy number and SS. Following our comprehensive investigation, no discernible causal relationship was identified between mtDNA copy number and SS in either the training or validation cohorts (inverse variance weighted, P  > .05). Similarly, the reverse Mendelian randomization analysis yielded negative results (inverse variance weighted, P  > .05). Furthermore, all analyses indicated an absence of horizontal pleiotropy or heterogeneity. Our analysis revealed no causal relationship between mtDNA copy number and SS.

The causal association of smoking, alcohol intake, and coffee intake with the risk of bacterial pneumonia: A Mendelian randomization study

BACKGROUND

At present, the association of smoking, alcohol intake, and coffee intake with the risk of bacterial pneumonia (BP) remains controversial. In this study, we used a 2-sample Mendelian randomization (MR) analysis to estimate the association of smoking, alcohol intake, and coffee intake with the risk of BP.

METHODS

We extracted genetic variants associated with smoking initiation and cigarettes per day from the Genome-Wide Association Study and Sequencing Consortium of Alcohol and Nicotine Use database (944,625 individuals). We also extracted genetic variants associated with past tobacco smoking, alcohol intake frequency, and coffee intake from the UK Biobank database (1,316,166 individuals). BP outcomes were chosen from the FinnGen genome-wide association studies (GWAS) database (7987 patients and 188,868 controls). The inverse variance-weighted method was used primarily to calculate odds ratios (OR) and 95% confidence intervals (CI). Sensitivity analysis using different approaches such as weighted median, MR Egger, and MR pleiotropy residual sum and outlier (MR-PRESSO) have been implemented, as well as leave-one-out analysis to identify pleiotropy.

RESULTS

The 2-sample MR analysis supported the causal association of genetically predicted cigarettes per day (OR: 1.23, 95% CI: [1.08-1.39], P < .01] and smoking initiation (OR: 1.22, 95% CI: [1.03-1.44], P = .02) with the risk of BP, but not past tobacco smoking, alcohol intake frequency, and coffee intake. Heterogeneity (P > .05) and pleiotropy (P > .05) tests provided confirmatory evidence for the validity of our MR estimates.

CONCLUSION

Our findings provide relevant evidence for a favorable causal association of genetically predicted smoking initiation and cigarettes per day with BP risk. However, there may not be a causal association between past tobacco smoking, alcohol intake, and coffee intake with increased BP incidence rates.

Ankylosing spondylitis and cardiovascular disease: A two-sample Mendelian randomization analysis

Epidemiological research has demonstrated that people suffering from ankylosing spondylitis (AS) have a greater chance of developing cardiovascular disease (CVD), though the potential link between AS genetics and CVD risk is uncertain. This research examined the potential link between CVD outcomes and AS which is genetically determined. A two-sample Mendelian randomization analysis was conducted using data from European population genome-wide association study of AS and CVD. We selected single nucleotide polymorphisms closely associated with AS genetic susceptibility as instrumental variables, and used inverse variance weighted as the main method to analyze the causal effects of AS on 7 CVDs (heart failure, atrial fibrillation, hypertension, ischemic stroke, etc). To further reinforce our results, we conducted replication analyses, sensitivity analyses, and instrumental variable strength assessments. In the European population, it was observed that AS genetic susceptibility was correlated with a higher risk of heart failure (odds ratios [OR] = 1.0128, 95% confidence intervals [CI]: 1.0037-1.0219, P = .0058), hypertension (OR = 1.0143, 95% CI: 1.0038-1.0248, P = .0073), and ischemic stroke (OR = 1.0151, 95% CI: 1.0049-1.0255, P = .0036). However, it was not associated with coronary heart disease, cardiomyopathy, valvular heart disease, or atrial fibrillation (all P > .05). A sensitivity analysis was conducted to validate the reliability of the results. Evidence from the European population has indicated a correlation between AS and heart failure, hypertension, and ischemic stroke. Further investigations should be conducted to explore the underlying mechanisms of action.

Deciphering proteins in Alzheimer's disease: A new Mendelian randomization method integrated with AlphaFold3 for 3D structure prediction

Hidden confounding biases hinder identifying causal protein biomarkers for Alzheimer's disease in non-randomized studies. While Mendelian randomization (MR) can mitigate these biases using protein quantitative trait loci (pQTLs) as instrumental variables, some pQTLs violate core assumptions, leading to biased conclusions. To address this, we propose MR-SPI, a novel MR method that selects valid pQTL instruments using Leo Tolstoy's Anna Karenina principle and performs robust post-selection inference. Integrating MR-SPI with AlphaFold3, we developed a computational pipeline to identify causal protein biomarkers and predict 3D structural changes. Applied to genome-wide proteomics data from 54,306 UK Biobank participants and 455,258 subjects (71,880 cases and 383,378 controls) for a genome-wide association study of Alzheimer's disease, we identified seven proteins (TREM2, PILRB, PILRA, EPHA1, CD33, RET, and CD55) with structural alterations due to missense mutations. These findings offer insights into the etiology and potential drug targets for Alzheimer's disease.

Testing the Causal Association Between Metabolic Syndrome and Periodontitis: A Two-sample Mendelian Randomisation Study

INTRODUCTION AND AIMS

Observational studies suggest an association between metabolic syndrome (MetS) and periodontitis. However, observational studies are susceptible to reverse causation and confounding factors, so the causality of this association is uncertain. Causal association between compounds of MetS and periodontitis has been well studied. Using Mendelian randomisation (MR), we aimed to comprehensively evaluate the bidirectional relationship between MetS as a whole and periodontitis and provide clinical insight.

METHODS

We used genetic instruments from the most comprehensive genome-wide association studies of European descent for MetS (n = 291,107) as well as periodontitis from both the FinnGen consortium (n = 195,395) and GeneLifestyle Interactions in Dental Endpoints (GLIDE, n = 45,563) consortium to investigate the causal relationship between MetS and periodontitis and vice versa. We used the inverse-variance weighted (IVW) method to derive the primary causal estimates and evaluated the robustness of our results with a series of sensitivity analyses.

RESULTS

MR analysis based on FinnGen consortium indicated a negative causal association of MetS on periodontitis (OR = 0.882, 95% CI = 0.791-0.983, P = .023), while MR analysis based on GLIDE consortium did not support a causal relation of MetS on periodontitis (OR = 0.986, 95% CI = 0.920-1.057, P = .697). These results were consistent after adjusting for potential confounding factors by multivariable MR analyses. Results from meta analysis did not support a causal association of MetS on periodontitis. Sensitivity analysis showed that there was no existence of pleiotropy. In the reverse direction, periodontitis showed no association with MetS.

CONCLUSIONS

Within the scope of this MR study, MetS and periodontitis are not causally related.

CLINICAL RELEVANCE

Further studies are needed to clarify the underlying mechanism between metabolic syndrome and periodontitis.

Therapeutic targets of antidiabetic drugs and kidney stones: A druggable mendelian randomization study and experimental study in rats

Diabetes is known to increase the risk of kidney stones, but the influence of antidiabetic drugs on this risk remains uncertain. Genetic instruments for antidiabetic drugs were identified as variants, which were associated with both the expression of genes encoding target proteins of drugs and glycated hemoglobin level (HbA1c). Here, we investigated the effect of antidiabetic drugs on kidney stones in a mendelian randomization (MR) framework, and further explore the potential effect on CaOx stone rat models induced by glyoxylic acid. Genetically proxied thiazolidinediones (PPARG agonists) significantly reduced the risk of kidney stones (OR = 0.42; P=0.004) per 1-SD decrement in HbA1c, while no significant association was noted in sulfonylureas, SGLT2 inhibitors, or GLP-1 analogs. Other antidiabetic drugs were not analyzed due to unclear pharmacological targets or no identified instruments. Additionally, PPARG agonists pioglitazone ameliorated CaOx nephrocalcinosis in glyoxylic acid-induced rats. The summary-data-based MR (SMR) results showed that PPARG mRNA expression in blood or kidney was not associated with kidney stone risk, and thus we performed mediation MR of PPARG agonists, circulating metabolites, and kidney stones. Among 249 circulating metabolites, we identified an indirect effect of PPARG agonists on kidney stones through increasing phospholipids to total lipids ratio in very large VLDL, with a mediated proportion of 6.87% (P = 0.018). Our study provided evidence that PPARG agonists reduced the risk of kidney stones partially via regulating lipid metabolism, and PPARG agonists may be a promising study subject in clinical studies for the prevention of kidney stones.

Association of Lactate with Risk of Cardiovascular Diseases: A Two-Sample Mendelian Randomization Study

Purpose

Studies consistently show abnormally high levels of lactate acid in cardiovascular disease patients, suggested that targeting lactate production may serve as potential strategies for the treatment in the future. However, observational results may be subject to residual confounding and bias.

Methods

This study used the dataset from GWAS database to examine confounding in epidemiologic associations between lactate and cardiovascular diseases. A genome-wide genetic association study using Mendelian randomization (MR) was performed from December 02, 2023 to January 15, 2024 to reduce confounding and enhance causal inference. Primary analysis was conducted using inverse-variance-weighted MR. All studies included patients predominantly of European ancestry.

Results

The association between lactate and cardiovascular diseases, including 60801 cases from coronary heart disease, 7018 cases from myocardial infarction, 14334 cases from coronary atherosclerosis, 60620 cases from atrial fibrillation, 54358 cases from hypertension, 71 cases from hypertrophic cardiomyopathy, 47309 cases from heart failure, 7055 cases from stroke, 7193 cases from cardioembolic ischemic stroke, 4373 cases from ischemic stroke caused by large vascular atherosclerosis, 2118 cases from pulmonary embolism, 1230 cases from peripheral artery disease, and 4620 cases from venous thromboembolism. Genetically predicted coronary atherosclerosis was associated with a higher risk of lactate level (OR = 1.950; 95% CI (0.087, 1.249); P = 0.024); this association was also evident for peripheral artery disease (OR = 1.003; 95% CI (0.000, 0.005); P = 0.021). No genetically predicted associations were noted for the other cardiovascular diseases.

Conclusion

The findings of this study provide genetic evidence supporting a higher risk of lactate level only in coronary atherosclerosis and peripheral artery disease. However, no genetic association between lactate level and the other cardiovascular diseases.

Integrative analysis revealed novel putative therapeutic targets of ulcerative colitis: Role of creatine

BACKGROUND

Ulcerative colitis (UC) is becoming a global burden. Previous observational studies have unveiled associations between serum metabolites and UC, but their causal relationship remains unclear.

METHODS

Serum samples from patients and mice with UC were utilized for untargeted metabolomics to identify UC-associated metabolites. Then, a two-sample mendelian randomization (MR) analysis was employed to estimate their causal relationship. Finally, mice with chronic colitis induced by dextran sodium sulfate (DSS) and macrophages were used to evaluate the protective role of creatine and underlying mechanism.

RESULTS

16 serum metabolites showed associations with UC after adjusting for confounders and multiple testing. Among them, creatine exhibited a robust protective effect against UC (OR=0.39; 95 % CI=0.27-0.56). Significant reduction of creatine was also observed in mice with acute UC induced by DSS. The inverse variance weighted (IVW) MR analysis further confirmed a causal effect of creatine on UC risk (OR IVW=0.45; 95 % CI: 0.27-0.76). Furthermore, creatine supplementation could significantly suppress weight loss, disease activity index, mucosal damage and the infiltration of macrophages in mice with chronic colitis. Remarkably, creatine promoted the polarization of bone marrow-derived macrophage (BMDM) towards M2 phenotype and upregulated the expression of il-10, il-12 and arg-1.

CONCLUSIONS

This study revealed a causal relationship between creatine and UC. Creatine supplementation ameliorated chronic colitis by inhibiting the colonic infiltration of macrophages and promoting its polarization towards M2 phenotype. These results offer new insight into the pathogenesis of UC, emphasizing a potential protective role of creatine for UC.

Deciphering the causal landscape: genetic insights into sporadic vestibular schwannoma risk factors through Mendelian Randomization

BACKGROUND

Sporadic vestibular schwannoma, a benign tumor affecting the vestibulocochlear nerve, poses significant health challenges due to its impact on hearing, balance, and facial nerve function. Despite known associations with genetic mutations and environmental factors, the causality between potential risk factors and sporadic vestibular schwannoma remains underexplored.

OBJECTIVE

This study aims to investigate the causal effects of various genetically predicted risk factors on sporadic vestibular schwannoma utilizing a Two-Sample Mendelian Randomization (MR) approach to enhance understanding of its etiology and inform prevention strategies.

METHODS

Leveraging data from genome-wide association studies (GWAS), we analyzed 29 risk factors across five categories: related diseases, lifestyle habits, nutritional status, learning ability, and laboratory indicators. The MR analysis employed instrumental variables (IVs) derived from single nucleotide polymorphisms (SNPs) to assess causal relationships, overcoming traditional observational study limitations.

RESULTS

Our findings highlight significant associations between sporadic vestibular schwannoma and factors such as ovarian cancer, uterine fibroids and lifestyle habits including dietary intake and alcohol consumption. Notably, higher educational attainment and specific laboratory indicators like high-density lipoprotein (HDL) cholesterol levels were linked to altered disease risk. These results suggest a multifaceted etiology involving hormonal, cardiovascular, gastrointestinal, immune, and metabolic pathways.

CONCLUSION

This comprehensive MR study provides novel insights into the diverse risk factors contributing to sporadic vestibular schwannoma, emphasizing the role of genetic predispositions, hormonal influences, and lifestyle choices in its development. The associations identified underscore the need for a multidisciplinary research approach and targeted public health strategies to mitigate sporadic vestibular schwannoma risk. Further research into the underlying mechanisms of these associations is crucial for developing effective interventions and improving patient outcomes.

Mendelian randomization study of the relationship between blood and urine biomarkers and lung cancer

Introduction

Identifying suitable biomarkers is crucial for exploring the pathogenesis, early screening, and therapeutic monitoring of lung cancer. This study aims to analyze comprehensively the associations between lung cancer and biomarkers in blood and urine.

Methods

Bidirectional two-sample Mendelian randomization (MR) was used to evaluate the potential causal relationships between blood and urine biomarkers and lung cancer. We obtained Single nucleotide polymorphisms (SNPs) related to lung cancer from the 2021 Finnish database of genome-wide association studies, including small cell lung cancer (SCLC), total non-small cell lung cancer (NSCLC), lung adenocarcinoma (LAC), and lung squamous cell carcinoma (LSCC).Data on blood and urine biomarkers were derived from the UK Biobank cohort, comprising 376,807 participants.

Results

We found a potential inverse causal relationship between total bilirubin and SCLC (β=-0.285, P=0.015, FDR=0.12). Urate was inversely associated with NSCLC (β=-0.158, P=0.004, FDR=0.036*). Serum calcium showed a possible inverse relationship with lung squamous cell carcinoma (β=-0.256, P=0.046, FDR=0.138), while urinary creatinine was positively associated (β=1.233, P=0.024, FDR=0.216). Non-albumin proteins (β=-0.272, P=0.020, FDR=0.180) and total protein (β=-0.402, P=0.009, FDR=0.072) were inversely related to lung squamous cell carcinoma. The AST/ALT ratio was positively associated with lung adenocarcinoma (β=0.293, P=0.009, FDR=0.072). Our reverse Mendelian randomization study found a positive causal association between small cell lung cancer and serum creatinine (β=0.022, P=0.002, FDR=0.018*), while it was inversely associated with the estimated glomerular filtration rate(eGFR)(β=-0.022, P=0.003, FDR=0.027*). A positive causal relationship was also observed with cystatin C (β=0.026, P=0.005, FDR=0.045*) and glycated hemoglobin HbA1c (β=0.013, P=0.014, FDR=0.028*). A negative causal relationship was observed with Gamma_glutamyltransferase (β=-0.013, P=0.019, FDR=0.152). For non-small cell lung cancer, a negative causal relationship was found with albumin (β=-0.024, P=0.002, FDR=0.016*), while a potentially positive causal relationship was observed with cystatin C (β=0.022, P=0.006, FDR=0.054). Possible negative causal relationships were also observed with phosphate (β=-0.013, P=0.008, FDR=0.072) and urinary potassium (β=-0.011, P=0.012, FDR=0.108), while a potential positive causal relationship was observed with C-reactive protein (β=0.013, P=0.040, FDR=0.280).Regarding lung squamous cell carcinoma, an inverse causal relationship was found with eGFR (β=-0.022, P=9.58e-06, FDR=8.62×10-5*), while a positive causal relationship was observed with serum creatinine (β=0.021, P=1.16e-4, FDR=1.05×10-3*). Potential positive causal relationships were observed with Urate (β=0.012, P=0.020, FDR=0.180), urea (β=0.010, P=0.046, FDR=0.141), and glycated hemoglobin HbA1c (β=0.020, P=0.049, FDR P=0.098), whereas a potential negative causal relationship was observed with sex hormone-binding globulin(SHBG) (β=-0.020, P=0.036, FDR=0.108).Lastly, adenocarcinoma was found to have a positive causal association with alkaline phosphatase (β=0.015, P=0.006, FDR=0.033*).

Conclusion

Our study provides a robust theoretical basis for the early screening and therapeutic monitoring of lung cancer and contributes to understanding the pathogenesis of the disease.

Association between genetically proxied PPARG activation and psoriasis vulgaris: a Mendelian randomization study

BACKGROUND

Psoriasis is a common autoimmune disease in clinical practice, and previous observational studies have suggested that PPARG agonists such as Pioglitazone may be potential therapeutic agents. However, due to interference from various confounding factors, different observational studies have not reached a unified conclusion. We aim to evaluate the potential use of PPARG agonists for treating psoriasis from a new perspective through drug-targeted Mendelian randomization (MR) analysis.

MATERIALS AND METHODS

This study includes data on 8,876 individuals for acute myocardial infarction from GWAS, and LDL cholesterol data from 343,621 Europeans. FinnGen contributed psoriasis vulgaris data for 403,972 individuals. The DrugBank10 databases function to identify genes encoding protein products targeted by active constituents of lipid-modifying targets. A two-sample MR analysis and summary-data-based MR (SMR) analysis estimated the associations between expressions of drug target genes and symptoms of psoriasis vulgaris. A multivariable MR study was further conducted to examine if the observed association was direct association.

RESULTS

SMR analysis revealed that enhanced PPARG gene expression in the blood (equivalent to a one standard deviation increase) was a protective factor for psoriasis vulgaris (beta = -0.2017, se = 0.0723, p = 0.0053). Besides, there exists an MR association between LDL mediated by PPARG and psoriasis vulgaris outcomes (beta = -3.9169, se = 0.5676, p = 5.17E-12). These results indicate that PPARG is a therapeutic target for psoriasis, suggesting that psoriasis may be a potential indication for PPARG agonists.

CONCLUSION

This study confirms that therapeutic activation of PPARG helps suppress the development of psoriasis. Psoriasis may be a new indication for PPARG agonists, such as Pioglitazone. In the future, new anti-psoriatic drugs could be developed targeting PPARG.

The causal relationship of DTI phenotypes and epilepsy: A two sample mendelian randomization study

OBJECTIVE

Clinical studies indicated a link between DTI imaging characteristics and epilepsy, but the causality of this connection had not been established. Therefore, we employed the Mendelian randomization analysis method to determine the causal relationship between DTI imaging characteristics and epilepsy.

METHOD

We used Mendelian randomization analysis to identify the causal relationship between brain structure and the risk of epilepsy. GWAS data of DTI phenotypes, focal epilepsy, and genetic generalized epilepsy (GGE) were utilized in the analysis.

RESULTS

Our study found that DTI imaging phenotypes had a causal risk relationship with epilepsy. These phenotypes had a statistical impact on the risk of epilepsy seizures. There were differences in DTI phenotype causality between GGE and focal epilepsy, which were associated with the clinical phenotype differences of the two types of epilepsy.

SIGNIFICANCE

Our study demonstrated that the diagnosis of subtypes could be assisted by comparing the differences in DTI phenotypes of specific brain regions. This meant that by studying the changes in brain regions before the onset of epilepsy, we might be able to intervene in epilepsy at an earlier stage.

PLAIN LANGUAGE SUMMARY

Our study used Mendelian randomization to explore the causal relationship between brain structure, as seen in DTI imaging, and epilepsy. We found that specific DTI phenotypes are linked to an increased risk of epilepsy seizures, with notable differences between genetic generalized epilepsy and focal epilepsy. This suggested that analyzing DTI phenotypes could help in diagnosing and potentially intervening in epilepsy earlier by finding brain changes before seizures begin.

Causal Role of Immune Cells in Chronic Obstructive Pulmonary Disease: A Two-Sample Mendelian Randomization Study

Accumulating evidence has highlighted the importance of immune cells in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, the understanding of the causal association between immunity and COPD remains incomplete due to the existence of confounding variables. In this study, we employed a two-sample Mendelian randomization (MR) analysis, utilizing the genome-wide association study database, to investigate the causal association between 731 immune-cell signatures and the susceptibility to COPD from a host genetics perspective. To validate the consistency of our findings, we utilized MR analysis results of lung function data to assess directional concordance. Furthermore, we employed MR-Egger intercept tests, Cochrane's Q test, MR-PRESSO global test, and "leave-one-out" sensitivity analyses to evaluate the presence of horizontal pleiotropy, heterogeneity, and stability, respectively. Inverse variance weighting results showed that seven immune phenotypes were associated with the risk of COPD. Analyses of heterogeneity and pleiotropy analysis confirmed the reliability of MR results. These results highlight the interactions between the immune system and the lungs. Further investigations into their mechanisms are necessary and will contribute to inform targeted prevention strategies for COPD.

Bidirectional influence between benign prostatic hyperplasia, prostate cancer, and prostatitis and mental disorders: two-sample and multivariate mendelian randomization analyses

BACKGROUND

We aimed to use Mendelian randomization (MR) to determine the causality between fifteen major mental disorders (MDs) and benign prostatic hyperplasia (BPH), prostate cancer (PCa), and prostatitis.

METHODS

The main MR analysis was performed using the inverse variance-weighted (IVW) method.

RESULTS

The study found that insomnia (odds ratio [OR], 1.6190; p = .0017) was significantly associated with an increased risk of BPH, and mood disorders (OR, 1.1590; p = .0221) was nominally associated with an increased risk of BPH. Conversely, BPH was suggestively associated with a low epilepsy risk (OR, 0.9988; p = .0043), and was nominally associated with an increased risk of insomnia (OR, 1.0061; p = .0291). Furthermore, attention deficit hyperactivity disorder (ADHD) was suggestively associated with a low PCa risk (OR = 0.9474; p = .0058). However, no causal relationship was observed between PCa and MDs. Finally, anorexia nervosa (OR, 1.1686; p = .0248) and depression (OR, 336.5383; p = .0308) were nominally positively correlated with prostatitis. Prostatitis was suggestively associated with increased risk of ADHD (OR, 1.0868; p = .0413).

CONCLUSION

Our findings provide clinicians with a basis for developing programs to prevent or treat MDs and prostatic diseases.

Unraveling the impact of irritability on esophageal diseases: Insights from multivariable Mendelian randomization analysis

BACKGROUND

Previous studies have suggested a potential association between irritability and the risk of various diseases. However, establishing a causal relationship has remained a significant challenge. To address this issue, we employed Mendelian randomization (MR), a sophisticated approach that leverages genotype data to emulate the conditions of randomized controlled trials. This method enables us to investigate the potential causal link between irritability and the susceptibility to esophageal diseases.

METHODS

We conducted an extensive multivariable MR analysis using summary-level data from genome-wide association studies (GWAS) encompassing various esophageal diseases, including gastroesophageal reflux disease (GERD), esophageal cancer (EC), and Barrett's esophagus. Both univariable and multivariable MR analyses were performed to elucidate and confirm the causal association between genetically predicted irritability and the incidence of esophageal diseases.

RESULTS

Based on our primary causal effects model utilizing MR analyses with the inverse-variance weighted (IVW) method, genetically predicted irritability was identified as a risk factor for GERD (OR = 2.413; 95 % CI: 1.678-3.470; P = 2.03E-06) and Barrett's esophagus (OR = 2.306; 95 % CI: 1.042-5.101; P = 0.039). However, irritability was not found to be associated with the risk of EC, even after adjusting for BMI, smoking initiation, and alcohol consumption.

CONCLUSION

The multivariable MR analysis performed in this study demonstrated a causal relationship between irritability and esophageal diseases. It is imperative to acknowledge the need for further large-scale prospective studies to validate these findings.