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Genetic evidence for causal association between migraine and dementia: a mendelian randomization study.

BACKGROUND: There is an association between migraine and dementia, however, their causal relationship remains unclear. This study employed bidirectional two-sample Mendelian randomization (MR) to investigate the potential causal relationship between migraine and dementia and its subtypes: Alzheimer's disease (AD), vascular dementia (VaD), frontotemporal dementia (FTD), and dementia with Lewy bodies (DLB). METHODS: Summary-level statistics data were obtained from publicly available genome-wide association studies (GWAS) for both migraine and five types of dementia. Single nucleotide polymorphisms (SNPs) associated with migraine and each dementia subtype were selected. MR analysis was conducted using inverse variance weighting (IVW) and weighted median (WM) methods. Sensitivity analyses included Cochran's Q test, MR pleiotropy residual sum and outlier (MR-PRESSO) analysis, the intercept of MR-Egger, and leave-one-out analysis. RESULTS: Migraine showed a significant causal relationship with AD and VaD, whereas no causal relationship was observed with all-cause dementia, FTD, or DLB. Migraine may be a potential risk factor for AD (odds ratio [OR]: 1.09; 95% confidence interval [CI]: 0.02-0.14; P = 0.007), while VaD may be a potential risk factor for migraine (OR: 1.04; 95% CI: 0.02-0.06; P = 7.760E-5). Sensitivity analyses demonstrated the robustness of our findings. CONCLUSION: Our study suggest that migraine may have potential causal relationships with AD and VaD. Migraine may be a risk factor for AD, and VaD may be a risk factor for migraine. Our study contributes to unraveling the comprehensive genetic associations between migraine and various types of dementia, and our findings will enhance the academic understanding of the comorbidity between migraine and dementia.

Humans↗

Lipid-lowering drugs and risk of rapid renal function decline: a mendelian randomization study.

BACKGROUND: Chronic kidney disease (CKD) patients face the risk of rapid kidney function decline leading to adverse outcomes like dialysis and mortality. Lipid metabolism might contribute to acute kidney function decline in CKD patients. Here, we utilized the Mendelian Randomization approach to investigate potential causal relationships between drug target-mediated lipid phenotypes and rapid renal function decline. METHODS: In this study, we utilized two methodologies: summarized data-based Mendelian randomization (SMR) and inverse variance-weighted Mendelian randomization (IVW-MR), to approximate exposure to lipid-lowering drugs. This entailed leveraging expression quantitative trait loci (eQTL) for drug target genes and genetic variants proximal to drug target gene regions, which encode proteins associated with low-density lipoprotein (LDL) cholesterol, as identified in genome-wide association studies. The objective was to investigate causal associations with the progression of rapid kidney function decline. RESULTS: The SMR analysis revealed a potential association between high expression of PCSK9 and rapid kidney function decline (OR = 1.11, 95% CI= [1.001-1.23]; p = 0.044). Similarly, IVW-MR analysis demonstrated a negative association between LDL cholesterol mediated by HMGCR and kidney function decline (OR = 0.74, 95% CI = 0.60-0.90; p = 0.003). CONCLUSION: Genetically predicted inhibition of HMGCR is linked with the progression of kidney function decline, while genetically predicted PCSK9 inhibition is negatively associated with kidney function decline. Future research should incorporate clinical trials to validate the relevance of PCSK9 in preventing kidney function decline.

Mendelian Randomization Analysis↗

Bioavailable testosterone reduces the risk of lung squamous cell carcinoma: a comprehensive data study.

BACKGROUND: The association between testosterone and lung cancer remains unclear. This study investigates the relationship between testosterone levels and lung cancer risk, focusing on bioavailable testosterone levels (BTLs), total testosterone levels (TTLs), and sex hormone-binding globulin (SHBG) in relation to lung cancer subtypes. METHODS: We utilized bidirectional and multivariable Mendelian randomization (MR) analyses based on genome-wide association studies (GWAS) to assess causal links. To validate the findings clinically, immunohistochemical (IHC) staining for androgen receptor (AR) expression and survival analyses were conducted on a cohort of 90 patients with lung squamous cell carcinoma (LUSC). RESULTS: MR analysis demonstrated that higher BTLs were significantly associated with a reduced risk of LUSC (OR&#x2009;=&#x2009;0.365, P&#x2009;=&#x2009;0.001), while no significant associations were observed for TTLs or SHBG. Reverse MR analysis found no causal effect of lung cancer on testosterone levels. Multivariable MR confirmed BTLs as an independent protective factor. In the clinical cohort, AR expression was significantly associated with better prognosis, showing improved median progression-free survival (12.3 vs. 9.0 months, P&#x2009;=&#x2009;0.01) and median overall survival (35.3 vs. 29.4 months, P&#x2009;<&#x2009;0.01). Cox regression identified AR expression as an independent protective factor for patient outcomes. However, study limitations include potential residual confounding, ethnic heterogeneity between European GWAS data and Asian clinical cohorts, and the lack of direct experimental validation. CONCLUSIONS: Our findings suggest that higher BTLs may play a protective role against LUSC. BTLs and AR expression show potential as valuable biomarkers for the diagnosis and prognostic assessment of LUSC.

Humans↗

Causal effects of sedentary behaviours on the risk of migraine: A univariable and multivariable Mendelian randomization study.

BACKGROUND: Migraine is a common and burdensome neurological disorder. The causal relationship between sedentary behaviours (SBs) and migraine remains instinct. We aimed to evaluate the roles of SBs including watching TV, using computer and driving in the risk of migraine. METHODS: We conducted a univariable and multivariable Mendelian randomization (MR) study based on summary datasets of large genome-wide association studies. The inverse variance weighted method was utilized as the primary analytical tool. Cochran's Q, MR-Egger intercept test, MR pleiotropy residual sum and outlier and leave-one-out were conducted as sensitivity analysis. Additionally, we performed a meta-analysis to combine the causal estimates. RESULTS: In the discovery analysis, we identified causal associations between time spent watching TV and an increased risk of migraine (p&#x2009;=&#x2009;0.015) and migraine without aura (MO) (p&#x2009;=&#x2009;0.002). Such causalities with increasing risk of migraine (p&#x2009;=&#x2009;0.005), and MO (p&#x2009;=&#x2009;0.006) were further verified using summary datasets from another study in the replication analysis. There was no significant causal association found between time spent using computer, driving and migraine or its two subtypes. The meta-analysis and multivariable MR analysis also strongly supported the causal relationships between time spent watching TV and an increased risk of migraine (p&#x2009;=&#x2009;0.0003 and p&#x2009;=&#x2009;0.034), as well as MO (p&#x2009;<&#x2009;0.0001 and p&#x2009;=&#x2009;0.0004), respectively. These findings were robust under all sensitivity analysis. CONCLUSIONS: Our study suggested that time spent watching TV may be causally associated with an increased risk of migraine, particularly MO. Large-scale and well-designed cohort studies may be warranted for further validation. SIGNIFICANCE STATEMENT: This study represents the first attempt to investigate whether a causal relationship exists between SBs and migraine. Utilizing MR analysis helps mitigate reverse causation bias and confounding factors commonly encountered in observational cohorts, thereby enhancing the robustness of derived causal associations. Our MR analysis revealed that time spent watching TV may serve as a potential risk factor for migraine, particularly MO.

Humans↗

Role of myeloid cells in mediating the effects of lipids on ulcerative colitis.

OBJECTIVE: To evaluate the causal relationship between lipids and ulcerative colitis (UC) through Mendelian Randomization (MR), and to further investigate the involvement of immune cells in mediating this process. METHODS: Utilizing summary statistics from genome-wide association studies (GWAS) of individuals with European ancestry, we analyzed the causal link between 179 lipid types and UC (2,569 UC cases and 453,779 controls) through Two-sample Mendelian randomization (2SMR) and Bayesian-weighted MR (BWMR). Based on this, a mediation screening of 731 immune cell phenotypes was conducted to identify exposure and mediator factors. Lastly, the role and proportion of immune cells in mediating the causal effects of lipids on UC were assessed via reverse MR (RMR) and two-step MR. RESULTS: The results of MR showed that there was a causal relationship between the six genetically predicted lipid types and UC (P <0.05), and the four immune cell phenotypes were identified as mediators of the association between lipids and UC. Notably, Phosphatidylcholine (PC) (16:0_0:0) served as the exposure factor, and myeloid cells CD11b on CD33+ HLA DR+ CD14dim acted as the mediator. Mediation analysis showed that CD11b on CD33+ HLA DR+ CD14dim had a mediation effect of -0.0205 between PC (16:0_0:0) and UC, with the mediation effect ratio at 15.38%. CONCLUSION: Our findings elucidate the causal effect of lipids on UC and identify the significant mediating role of myeloid cells CD11b on CD33+ HLA DR+ CD14dim in regulating UC through PC (16:0_0:0), offering new pathways and strategies for UC clinical treatment.

Humans↗

Mendelian randomization underscores the importance of clinical nursing in mitigating anxiety and panic attack risks among low-educated populations.

Considering the complex and underexplored interplay between educational attainment (EA) and the prevalence of anxiety and panic attacks, which carries significant societal implications, we have designed a two-sample Mendelian randomization (MR) study. The primary objective of this research is to elucidate the causal relationship between education level and the risk of anxiety and panic attacks, thereby providing novel insights for clinical and nursing strategies. Our study adheres to the STROBE-MR guidelines and employs a classical two-sample MR analysis to investigate the causal relationship between EA (exposure) and the occurrence of anxiety/panic attacks (outcome). The data for 8 education-related phenotypes, along with anxiety and panic attack outcomes, were sourced from European population-based Genome-wide association studies databases. To ensure robustness, we applied 5 distinct MR analytical methods, supplemented by comprehensive sensitivity analyses, heterogeneity assessments, and evaluations of reverse causality bias to uphold rigorous quality control standards. Our findings, robust across various MR methods and consistent after inverse variance-weighted and false discovery rate (FDR) corrections, indicate a significant association between lower EA and an increased risk of anxiety or panic attacks. Specifically, individuals with no formal qualifications exhibited a higher risk (P-value&#x2005;=&#x2005;.005, OR&#x2005;=&#x2005;1.017, 95% CI&#x2005;=&#x2005;1.005-1.029, FDR&#x2005;=&#x2005;0.011). In contrast, higher levels of education were associated with a reduced risk: College or University degree (P-value&#x2005;<&#x2005;.01, OR&#x2005;=&#x2005;0.989, 95% CI&#x2005;=&#x2005;0.984-0.995, FDR&#x2005;=&#x2005;0.0007), EA (P-value&#x2005;<&#x2005;.01, OR&#x2005;=&#x2005;0.999, 95% CI&#x2005;=&#x2005;0.998-0.9995, FDR&#x2005;=&#x2005;0.0009), and A levels/AS levels or equivalent (P-value&#x2005;=&#x2005;.011, OR&#x2005;=&#x2005;0.988, 95% CI&#x2005;=&#x2005;0.978-0.997, FDR&#x2005;=&#x2005;0.019). These conclusions were consistently supported by at least 4 MR methods and successfully passed all quality control checks. Our study demonstrates a negative correlation between years of education and the risk of anxiety and panic attacks, suggesting that clinical nursing and patient education efforts should prioritize tailored psychological support and patient communication for individuals with lower EA. This population warrants enhanced attention and more compassionate care to mitigate their elevated risk of anxiety-related disorders.

Humans↗

Genetically predicted childhood traits and parental health and risk of pediatric psychiatric disorders: A 2-sample Mendelian randomization study.

The etiology of pediatric psychiatric disorders is complex, involving intergenerational influences and a child's own developmental health. We aimed to investigate the potential effects of genetically predicted childhood traits (childhood obesity, absence epilepsy, intelligence) and parental health traits (longevity, Alzheimer disease, severe depression) on the risk of several childhood and adolescent psychiatric disorders. We employed a 2-sample Mendelian randomization (MR) design using summary statistics from large-scale genome-wide association studies. Data for parental health exposures were primarily from the UK Biobank. Data for childhood trait exposures were from various consortia. Data for outcomes - conduct disorder, mixed conduct and emotional disorders, attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), and broader behavioral/emotional and social disorders - were sourced from FinnGen and the Psychiatric Genomics Consortium, among others. We used the inverse-variance weighted method for the primary analysis, with MR-Egger, weighted median, and weighted mode as additional analyses. To test the robustness of the results, we conducted sensitivity analyses using MR-Egger regression, Cochran Q test for heterogeneity, the MR-pleiotropy residual sum and outlier test, and a leave-one-out analysis. Genetic liability for childhood obesity was associated with an increased risk of ASD (odds ratio&#x2005;=&#x2005;1.06, P&#x2005;=&#x2005;.016) and ADHD (odds ratio&#x2005;=&#x2005;1.09, P&#x2005;=&#x2005;.026), even though these associations did not withstand multiple testing correction. No other robust, statistically significant causal associations were identified. Sensitivity analyses showed limited evidence of bias from horizontal pleiotropy for the main findings. Our findings provide MR evidence supporting potential links from genetic liability for childhood obesity to increased risks of ASD and ADHD. These results highlight the importance of considering a child's early-life health trajectory in the etiology of pediatric psychiatric disorders.

Humans↗

Causal relationships between oral-gut microbiome and bone neoplasm-related phenotypes: Insights from bidirectional Mendelian randomization.

The human oral and gut microbiota are the 4 largest microbial communities in the body and play crucial roles in maintaining homeostasis and influencing disease. Observational studies have suggested links between these microbiota and bone neoplasm-related phenotypes, but establishing causality has been challenging due to confounding factors and reverse causality. We conducted a bidirectional, 2-sample Mendelian randomization (MR) study to investigate evidence consistent with a potential causal association between the saliva and gut microbiota and various bone neoplasm-related phenotypes. Genetic instruments for saliva and gut microbiota were sourced from large genome-wide association studies. Inverse variance weighted was the primary MR method, supplemented by 4 other MR techniques. Sensitivity analyses, including MR-Egger regression, were performed to assess pleiotropy and heterogeneity. In the forward MR analysis, Veillonella parvula from the saliva microbiota was associated with a decreased risk of bone and connective tissue neoplasms (&#x3b2;: -0.236, 95% CI: [-0.275, -0.197], P&#x2005;=&#x2005;8.20E-33). MR analyses identified genetically predicted associations between several microbial taxa and bone neoplasm-related phenotypes. Reverse MR analyses showed that genetic liability to bone neoplasm-related phenotypes was associated with variation in the composition of the oral (e.g., Order Bacteroidales, Rothia mucilaginosa) and gut microbiota (e.g., Class Methanobacteria, Genus Eubacterium oxidoreducens group). Sensitivity analyses confirmed the robustness of these findings, as no statistical evidence of substantial heterogeneity or directional horizontal pleiotropy was detected. This study provides genetic evidence supporting a bidirectional causal relationship between specific saliva and gut microbiota and bone neoplasm-related phenotypes. Our findings identify several microbial taxa as potential candidates for future biomarker development and therapeutic investigation in bone neoplasm-related phenotypes. However, these genetically informed associations require further mechanistic, experimental, and prospective clinical validation before clinical application.

Humans↗

Assessing the comorbidity between asthma and depression through polygenic risk scoring and time-to-event models.

BACKGROUND: Patients with asthma have an increased risk of developing depression, affecting their quality of life. To date, the processes contributing to this comorbidity remain unclear. METHODS: We integrated two large genome-wide association studies (88,486 patients with asthma and 447,859 controls; 412,024 patients with depression and 1,587,577 controls) with cross-sectional and longitudinal information available from the All of Us Research Program (N&#x2009;=&#x2009;87,167) through polygenic risk scoring (PRS), Cox proportional-hazards models, one-sample Mendelian randomization (MR), and gene-set and drug-repurposing analyses. RESULTS: We observed that depression PRS was associated with increased asthma risk (hazard ratio, HR&#x2009;=&#x2009;1.13, 95% CI&#x2009;=&#x2009;1.09-1.17), also when accounting for comorbidity status (HR&#x2009;=&#x2009;1.08, 95% CI&#x2009;=&#x2009;1.04-1.12). Conversely, the effect of asthma PRS was null after accounting for comorbidity status. One-sample MR analysis showed an effect of depression genetic liability on asthma, ranging from beta&#x2009;=&#x2009;0.36&#x2009;&#xb1;&#x2009;0.03 when considering a linear relationship to beta&#x2009;=&#x2009;3.21&#x2009;&#xb1;&#x2009;0.31 when considering possible nonlinear relationships. Conversely, the effect of asthma genetic risk on depression was null after accounting for potential confounders. The gene-set analyses showed that asthma and depression polygenic risks share biological processes, molecular functions, and cellular components related to the immune system and the lung-brain axis. CONCLUSIONS: Genetic predisposition contributes to asthma-depression comorbidity through direct effects and shared pathogenic processes. These findings highlight the potential to develop targeted interventions to prevent and treat the co-occurrence of respiratory and neuropsychiatric disorders.

Comorbidity↗

Mendelian randomization reveals causal relationships between cytokines and male reproductive diseases.

This study aims to explore the causal links between cytokines and four male reproductive disorders, namely abnormal spermatozoa (AS), male infertility, erectile dysfunction (ED), and hyperplasia of prostate (HP), employing a two-sample Mendelian randomization (MR) approach. Genetic associations with male reproductive diseases were derived from the IEU OpenGWAS project, with cytokine data from two GWASs focused on the human proteome and cytokines. Estimations were derived using inverse variance weighting, MR-Egger regression, weighted median, weighted model, and simple mode. Furthermore, the robustness of the findings was evaluated through Cochran's Q-test, MR-Egger regression, and leave-one-out sensitivity analysis. Fifteen unique cytokines were identified as having causal relationships with the risk of four male reproductive disorders. Specifically, for AS, interleukin-22 (IL-22), IL-12, and macrophage migration inhibitory factor were negatively correlated with AS, while tumor necrosis factor &#x3b2; levels were positively correlated with AS. In the context of male infertility, IL-2 receptor antagonist levels, IL-34, and granulocyte-colony stimulating factor levels were positively linked to male infertility, whereas IL-21 showed a negative relationship. Regarding ED, IL-19, IL-1&#x3b2;, and eotaxin levels were negatively associated with ED risk, while macrophage inflammatory protein 1&#x3b2; (MIP-1&#x3b2;) levels and interferon gamma-induced protein 10 levels were positively associated. As for HP, stromal-cell-derived factor 1&#x3b1; levels and MIP-1&#x3b1; levels revealed negative associations with HP. In conclusion, this MR analysis revealed that several cytokines were causally associated with male reproductive diseases and could be valuable in offering new insights for further mechanistic and clinical investigations of cytokines-associated male reproductive diseases.

Male↗

Causal relationships between modifiable risk factors and heart failure: A comprehensive Mendelian randomization study.

Heart failure threatens human health across the globe. Comprehensively identifying its risk factors has public health importance. This work utilized the Mendelian randomization (MR) method to evaluate the effects of over 200 modifiable factors on heart failure. The data from genome-wide association studies (GWAS) was used, with the sample size ranging from 711 to 1232,091. Two distinct GWAS datasets for heart failure were employed for results validation. The inverse variance weighted (IVW) method was used and other supplementary models were employed for comparison. Sensitivity analysis was conducted to verify the results. After integrating the MR estimates derived from heart failure GWAS datasets from integrative epidemiology unit (IEU) and Finngen, we found that body measurement indices like body mass index, whole body fat mass, trunk fat mass, basal metabolic rate, body fat percentage, waist circumference, and waist-hip ratio, were associated with a higher risk of heart failure. Similarly, smoking behavior, sedentary behavior, overall health rating, and type 2 diabetes were determined to increase the risk of heart failure. In contrast, college or university degree showed a protective effect on heart failure. Among these significant findings, body mass index, whole body fat mass, trunk fat mass, basal metabolic rate, body fat percentage, overall health rating, smoking initiation, waist circumference, lifetime smoking index, college or university degree, sedentary behavior, waist-hip ratio, and type 2 diabetes were replicated validated. This MR work figured out that obesity, socioeconomic factors, lifestyle factors, and metabolic features showed broad relations with heart failure. The findings would provide evidence for future policy development for the management of heart failure.

Humans↗

Asthma causally affects the brain cortical structure: a Mendelian randomization study.

OBJECTIVE: The potential causal relationship between asthma and brain structures remains uncertain. We performed a two-sample Mendelian randomization to investigate the causal effects of various asthma phenotypes - unspecified asthma, moderate-to-severe asthma, childhood-onset asthma, and adult-onset asthma (AOA) - on cerebral cortex structure. METHODS: We utilized phenotype data derived from genome-wide association studies (GWASs). The ENIGMA Consortium GWAS provided outcome variables for surface area (SA) and thickness across the whole brain and 34 region-specific areas of the cerebral cortex. Using the inverse variance-weighted method as our primary estimation approach, we employed several techniques, including Cochran's Q statistic, the MR-PRESSO global test, MR-Egger, and weighted median, to assess heterogeneity and pleiotropy, thereby ensuring the robustness of our findings. Additionally, we conducted enrichment analyses of gene sets with causal effects on cortical structure and applied bioinformatics techniques to construct interaction networks and identify hub nodes. RESULTS: At the global level, AOA was associated with a significant reduction in full cortical SA (&#x3b2;&#xa0;=&#xa0;-58.49 mm2, p&#xa0;=&#xa0;0.017). In regional analyses, moderate-to-severe asthma exhibited a more pronounced impact on the cerebral cortex compared to other phenotypes. Enrichment analysis revealed that pathways implicated in brain morphology among asthma patients were primarily linked to immune and inflammation-driven pathways. CONCLUSIONS: Our findings provide new evidence supporting a causal relationship between asthma and alterations in cortical structure, offering potential explanations for cognitive and psychiatric impairments observed in individual post-asthma.

Humans↗

Can we identify people with Alzheimer's disease from examination of the eye? A bidirectional Mendelian randomization (MR) study.

BACKGROUND: Neurodegeneration in Alzheimer's disease (AD) is thought to be driven by amyloid-beta and tau deposition in the cerebral vasculature and brain. As the eye is an extension of the central nervous system, this study aimed to determine which neurovascular and neuroretinal changes in the eye are caused by AD rather than associations of the disease. METHODS: Bidirectional two-sample univariable and multivariable Mendelian randomization (MR) methods were applied. Instrumental variables were derived from genome-wide association studies (GWAS) of AD and the following ocular features: thickness measurements of central macula (MT), retinal nerve fibre layer (mRNFL), ganglion cell-inner plexiform layer (mGCIPL), outer nuclear layer (ONL), inner segment layer (IS), and outer segment (OS) from macular region OCT scans; arteriolar tortuosity (AT), venular tortuosity (VT), venular width (VW), fractal dimension (FD), vertical cup-to-disc ratio (VCDR), optic cup area (OCA), and optic disc area (ODA) derived from other imaging methods. RESULTS: There was strong evidence that genetic liability to AD affected the retinal vasculature by specifically increasing AT (&#x3b2; = 0.007;95%CI=0.002,0.011;p-value=0.005) in UK Biobank participants (n=52,798). AD may influence the mRNFL (&#x3b2;=-0.047,95%CI=-0.119,0.023,p-value=0.18) and mGCIPL (&#x3b2;=-0.061;95%CI=-0.14,0.025,p-value=0.16) of the inner retina and OS layer (&#x3b2; = 0.044;95%CI=-0.0001,0.08;p-value=0.05) but the evidence was weak. Multivariable MR analysis showed that a causal relationship between optic disc area and AD (OR=0.76;95%CI=0.62,0.93,p-value=0.009) was probably mediated by refractive error. CONCLUSION: Early cerebrovascular signs of AD may be detected by examination of the eye. Further investigation is required to determine the clinical utility of eye screening for dementia.

Humans↗

Positive association between apolipoprotein B and colorectal cancer risk: Findings from a 14-year follow-up cohort study and Mendelian randomization analyses.

BACKGROUND: The effects of lipid traits on colorectal cancer (CRC) risk and the extent to which obesity may modify these effects remain unclear. OBJECTIVE: To examine the associations between lipid traits and CRC risk using an observational study and Mendelian randomization (MR) analyses, and the role of weight status in the potential associations. METHODS: In the Guangzhou Biobank Cohort Study (GBCS), lipid profiles were measured during 2003-2008, and CRC events were identified through record linkage with the cancer registry. MR analyses assessed the causal effects of lipid traits on CRC using a genome-wide association study meta-analysis of 185,616 Europeans. RESULTS: Among 28,576 GBCS participants followed until 2020, 599 CRC events occurred. Participants in the highest quartile of apolipoprotein B (apoB) had a higher CRC risk (hazard ratio [HR] 1.43, 95% CI&#xa0;1.02-2.01). This association remained in those with overweight/obesity (HR 2.21, 95% CI 1.28-3.83). MR analyses supported a detrimental effect of apoB on CRC (odds ratio 1.12 per 1 SD, 95% CI 1.02-1.22). MR analyses also showed positive associations for total cholesterol and the apoB/apolipoprotein A-I ratio, which were not significant in the observational study. CONCLUSION: Higher apoB levels were associated with an increased CRC risk in both observational and MR analyses, suggesting a potential role of apoB in CRC prevention, especially among participants with overweight/obesity. However, the limitations of single-time lipid measurements and the use of different ancestries across study designs indicate the need for further research to confirm the robustness and generalizability of the findings.

Humans↗

Genetically predicted CXCL16 expression is associated with Parkinson's disease risk and peripheral immune cell dysregulation: a two-sample mendelian randomization study.

BACKGROUND: Parkinson's disease (PD) is a progressive neurodegenerative disorder with limited disease-modifying therapies. PANoptosis, an integrated form of programmed cell death involving apoptosis, pyroptosis, and necroptosis, has been implicated in neuroinflammation-related neurodegeneration. However, the roles of PANoptosis-related genes in PD remain unclear. METHODS: We performed two-sample Mendelian randomization (MR) using cis-eQTL instruments from the eQTLGen Consortium for 30 PANoptosis-related genes, with PD GWAS data from Nalls et al. 2019 as the outcome. Instrumental variables were selected using a hierarchical strategy, with genome-wide significant cis-eQTLs as primary instruments and a relaxed threshold applied only for genes with fewer than three independent SNPs. Sensitivity analyses included MR-Egger, weighted median, MR-PRESSO, MR-RAPS, and leave-one-out analyses. SMR/HEIDI testing and two-step MR mediation using 731 peripheral immune traits were also performed. RESULTS: Genetically predicted higher CXCL16 expression was associated with increased PD risk (OR&#x2009;=&#x2009;1.115, 95% CI 1.060-1.173, p&#x2009;=&#x2009;2.4&#x2009;&#xd7;&#x2009;10-5), while higher FADD expression was associated with reduced PD risk (OR&#x2009;=&#x2009;0.861, 95% CI 0.790-0.939, p&#x2009;=&#x2009;7.1&#x2009;&#xd7;&#x2009;10-4). CASP1 and IFI27 were nominally significant and considered exploratory. Sensitivity analyses were directionally consistent, although MR-Egger estimates were imprecise. SMR/HEIDI supported CXCL16. Exploratory mediation analysis identified 63/66 candidate immune mediators after FDR correction. CONCLUSION: These findings provide MR-based genetic evidence linking CXCL16 expression to PD risk, with exploratory mediation through peripheral immune phenotypes. The CXCL16-immune cell-PD axis warrants further experimental validation.

Humans↗

Causal associations between inflammatory bowel disease and sepsis: a two-sample Mendelian randomization study.

BACKGROUND: Recent observational studies have revealed an inconclusive correlation between inflammatory bowel disease (IBD) and sepsis, accompanied by an uncertain understanding of the causal relationship between the two. To investigate the causality between IBD and sepsis, we employed a two-sample Mendelian randomization (MR) approach. METHODS: A genome-wide significant threshold (P&#x2009;<&#x2009;5&#x2009;&#xd7;&#x2009;10-8) was achieved in order to identify single nucleotide polymorphisms (SNPs) as instrumental variables (IVs) for two types of IBD, such as Crohn's disease (CD) and ulcerative colitis (UC). Subsequently, the selected SNPs were assessed in relation to three categories of sepsis, namely sepsis, sepsis (critical care), and sepsis (28-day death in critical care). An inverse-variance weighted (IVW) estimation of MR was conducted, followed by sensitivity analysis on multiple dimensions. RESULTS: There was a significant association between genetic liability to CD (IVW: OR, 1.246; 95% CI, 1.090-1.423; P&#x2009;=&#x2009;0.0012) with sepsis (28-day death in critical care), but not with sepsis (critical care) and sepsis. Whereas UC showed slightly, yet statistically insignificant, higher risk for sepsis (IVW: OR, 1.031; 95% CI, 0.988-1.064; P&#x2009;=&#x2009;0.064). CONCLUSION: Our study offers genetic evidence that supports a substantial causal relationship between CD and sepsis (28-day death in critical care). To enhance the specificity and objectivity of future research findings, it is recommended to specify the types of IBD and the severity of sepsis. Furthermore, the genetic risk loci related may become potential drug development targets.

Humans↗

Genetically proxied circulating PD-1/PD-L1 levels and broadly defined myocarditis: A bidirectional Mendelian randomization study with exploratory lipidomic analyses.

Myocarditis is an inflammatory myocardial disease with potentially severe outcomes. Programmed cell death protein 1 (PD-1) and programmed death-ligand 1 (PD-L1) regulate immune tolerance, but the association between lifelong genetically proxied circulating PD-1/PD-L1 levels and broadly defined myocarditis remains uncertain. We investigated these associations and explored related plasma lipid species. We conducted bidirectional 2-sample Mendelian randomization using proteomic genome-wide association data from the UK Biobank Pharma Proteomics Project and INTERVAL. FinnGen Release 10 was the primary broadly defined myocarditis outcome, and an independent myocarditis genome-wide association study (GCST90018882) provided outcome-level validation. Complementary estimators, heterogeneity and pleiotropy diagnostics, influence analyses, MR-RAPS, and supportive meta-analyses were performed. Associations with 179 plasma lipid species were examined in exploratory analyses. Higher genetically proxied circulating PD-L1 was inversely associated with broadly defined myocarditis in UKB-PPP (odds ratio [OR] 0.834, 95% confidence interval [CI] 0.698-0.995; P&#x2005;=&#x2005;.0441), and the independent INTERVAL analysis yielded a concordant inverse estimate (OR 0.619, 95% CI: 0.434-0.883; P&#x2005;=&#x2005;.0083); no clear association was observed for PD-1. The MR-RAPS estimate retained the inverse direction; estimates against the independent broadly defined myocarditis dataset were also inverse, and supportive meta-analyses across protein and outcome sources yielded inverse pooled estimates. Reverse MR did not support effects of broadly defined myocarditis liability on circulating PD-1 or PD-L1. Exploratory lipid analyses identified nominal associations requiring confirmation. Higher genetically proxied circulating PD-L1 may be associated with a lower risk of broadly defined myocarditis, supporting further investigation of PD-L1-related immune regulation. These findings do not directly estimate the effects of pharmacologic PD-1/PD-L1 blockade. The lipid findings are hypothesis-generating.

Myocarditis↗

Uncovering metabolite-immune interactions in the pathogenesis of psoriatic arthritis: A 2-sample Mendelian randomization study.

PsA is a chronic inflammatory joint condition associated with psoriasis, and its underlying mechanisms are not fully elucidated. Serum metabolites, as direct reflections of metabolic status, may influence disease progression by regulating immune cell function; however, the causal relationships and specific pathways require further investigation. The present investigation utilized a 2-sample bidirectional MR methodology, leveraging extensive pooled GWAS data to thoroughly evaluate the causal relationships between 1440 serum metabolites and PsA. Additionally, mediation MR analysis was performed to explore the possible mediating effects of 731 immune cell characteristics. In the primary analysis, inverse-variance weighted was employed, and this was further supported by various sensitivity analyses to confirm the reliability of the findings. The genetic method to infer causality analysis revealed significant positive causal associations between 10 serum metabolites and PsA risk, with quinolinate levels demonstrating the most significant correlation (OR&#x2005;=&#x2005;1.56, 95% CI: 1.26-1.93); while 4 metabolites (e.g., citrate levels, OR&#x2005;=&#x2005;0.74, 95% CI: 0.61-0.89) exhibited protective effects. Regarding immune cells, 6 cellular features (e.g., CD20 on B cells) were positively correlated with disease risk, whereas 5 features (primarily HLA-DR expression on monocyte subsets) showed negative correlations. Mediation analysis identified 3 significant pathways,the percentage of the effect explained by the mediator: N6,N6,N6-trimethyllysine levels mediated via B cells (CD20 on IgD+ CD38br), with a proportion of 33.2%; 1-stearoyl-2-docosahexaenoyl-GPE (18:0/22:6) levels mediated through monocytes (HLA-DR on CD14- CD16-) with a 32.0% proportion; the unknown metabolite X-24736 also mediated 42.1% of the protective effect via the same monocyte phenotype. This study revealed that elevated amino acid-related metabolites and glycerophospholipids significantly increase PsA risk through immune cell effects. These are closely associated with PsA pathogenesis and may serve as potential biomarkers. The novel findings underscore metabolic-immune interactions as targets for biomarkers and therapies in PsA, advancing personalized medicine.

Humans↗