Potential Causal Relationship Research Articles

Explore the genetic exposure to alopecia areata.

Alopecia areata is an autoimmune hair loss disorder with an incompletely understood etiology. Although trace elements, serum metabolites, and inflammatory factors are implicated in the disease, the potential causal relationships between these factors and alopecia areata require further investigation. This study employed Mendelian randomization (MR), utilizing data from genome-wide association studies, to explore the causal relationships between 15 trace elements, 1400 serum metabolites, and 91 inflammatory factors and alopecia areata. The analysis was conducted using the inverse variance weighted (IVW) method complemented by various sensitivity analyses, including Cochran's Q test, MR-Egger regression intercept test, MR-PRESSO global test, and leave-one-out analysis, to assess the robustness of the results. MR analysis indicated a negative correlation between copper levels and the risk of developing alopecia areata (odds ratio=0.86, 95% confidence interval: 0.75-0.99, p=0.041). Additionally, causal relationships were identified between 15 serum metabolites and 6 inflammatory factors and the risk of alopecia areata (IVW, all p values<0.05). This study provides genetic evidence of the relationships between trace elements, serum metabolites, and alopecia areata, underscoring the potential value of targeted therapeutic strategies and preventive measures. Future research should expand to diverse populations and further explore the specific roles of these biomarkers in the disease mechanism.

Genetic support for the causal association between 91 circulating inflammatory proteins and atopic dermatitis: A two-sample Mendelian randomization trial.

Atopic dermatitis (AD) is a refractory disease that occurs in clinical practice. One of the most common inflammatory skin diseases, its occurrence and development are related to inflammation. Nevertheless, the precise nature of the relationship between circulating inflammatory proteins and AD remains uncertain. A two-sample MR analysis was performed to determine the causal relationship between the expression of 91 circulating inflammatory proteins and AD by using genome-wide association study (GWAS) summary statistics data from the FinnGen consortia. The robustness of the MR results was assessed by means of sensitivity analysis. The causal relationship between the expression of nine specific circulating inflammatory proteins and AD was corroborated by the inverse variance weighted (IVW) method. The findings indicated that three circulating inflammatory proteins, namely, interleukin-18 receptor 1 [OR (CI)=1.08 (1.05-1.11); p=0.000001)], interleukin-8 [OR (CI)=1.07 (1.00-1.14); p=0.036244)], and tumor necrosis factor ligand superfamily member 14 [OR (CI)=1.05 (1.00-1.10); p=0.036842)], were positively correlated with AD. Additionally, six circulating inflammatory proteins were negatively correlated with AD: the T-cell surface glycoprotein CD5 [OR (CI)=0.89 (0.84-0.95); p=0.000191)], macrophage colony-stimulating factor 1 [OR (CI)=0.93 (0.88-0.99); p=0.031422)], fractalkine [OR (CI)=0.91 (0.85-0.97); p=0.003067)], interleukin-24 [OR (CI)=0.91 (0.83-0.99); p=0.031673)], signaling lymphocytic activation molecule [OR(CI)=0.94 (0.89-1.00); p=0.039818)], and urokinase-type plasminogen activator [OR(CI)=0.95 (0.90-1.00); p=0.037037)]. This study confirms the potential causal relationship between circulating inflammatory proteins and AD and provides guidance for the clinical diagnosis and treatment of AD.

Absence of Causal Relationship Between Levels of Unsaturated Fatty Acids and ADHD: Evidence From Mendelian Randomization Study.

Previous research suggests a potential link between unsaturated fatty acids (UFAs) and ADHD, but the causal relationship remains uncertain. This study aims to investigate the causal association between ADHD and UFAs using Mendelian randomization (MR) analysis. Summary data from genome-wide association studies were used to estimate the concentration of circulating UFAs, including Monounsaturated Fatty Acids (MUFAs), Polyunsaturated Fatty Acids (PUFAs), Omega-3 PUFAs, Omega-6 PUFAs, Linoleic Acid (LA), and Docosahexaenoic Acid (DHA). Data from the Psychiatric Genomics Consortium, including both childhood and adult ADHD, were respectively used to examine the relationship between genetically predicted UFAs levels and ADHD. Various MR methods, including Inverse-variance weighted (IVW), MR Pleiotropy RESidual Sum and Outlier, MR-Egger, weighted median, and weighted mode, were employed to assess heterogeneity and pleiotropy. The IVW revealed only nominal evidence suggesting a potential causal relationship between genetically predicted PUFAs (OR = 0.92, 95% CI [0.85, 0.99], p = .031), Omega-6 PUFAs (OR = 0.90, 95% CI [0.83, 0.98], p = .020), and LA levels (OR = 0.90, 95% CI [0.82, 0.98], p = .021) with childhood ADHD risk. However, after false discovery rate correction, the p-values for PUFAs, Omega-6 PUFAs, and LA levels all exceeded the threshold for significance. For adult ADHD, we did not find any significant associations between the six circulating UFA levels and adult ADHD. Our findings do not support a causal relationship between UFAs levels and ADHD. This suggests that UFAs supplements may not be effective in improving ADHD symptoms and importantly, it appears that UFAs levels may not have a long-term effect on ADHD.

Rheumatoid arthritis and adverse pregnancy outcomes: a bidirectional two-sample mendelian randomization study

BackgroundThere is growing evidence of bidirectional associations between rheumatoid arthritis and adverse pregnancy outcomes (APOs) in observational studies, but little is known about the causal direction of these associations. Therefore, we explored the potential causal relationships between rheumatoid arthritis and APOs using a bidirectional two-sample Mendelian randomization (MR) in European and Asian populations.MethodsWe conducted a bidirectional two-sample Mendelian randomization analysis using available summary statistics from released genome-wide association studies. Summary statistics for instrument–outcome associations were retrieved from two separate databases for rheumatoid arthritis and adverse pregnancy outcomes, respectively. The inverse-variance weighted method was used as the primary MR analysis, and cML-MA-BIC was used as the supplementary analysis. MR-Egger, MR pleiotropy residual sum and outlier (MR-PRESSO), and Cochran Q statistic method were implemented as sensitivity analyses approach to ensure the robustness of the results.ResultsOur study showed that a higher risk of rheumatoid arthritis in the European population was associated with gestational hypertension (OR: 1.04, 95%CI: 1.02–1.06), pre-eclampsia (OR: 1.06, 95%CI: 1.01–1.11), fetal growth restriction (OR: 1.08, 95%CI: 1.04–1.12), preterm delivery (OR:1.04, 95%CI: 1.01–1.07). Furthermore, we found no evidence that APOs had causal effects on rheumatoid arthritis in the reverse MR analysis. No association between rheumatoid arthritis and APOs was found in East Asian population. There was no heterogeneity or horizontal pleiotropy.ConclusionsThis MR analysis provides the positive causal association from rheumatoid arthritis to gestational hypertension, pre-eclampsia, fetal growth restriction and preterm delivery genetically. It highlights the importance of more intensive prenatal care and early intervention among pregnant women with rheumatoid arthritis to prevent potential adverse obstetric outcomes.

The plasma lipids with different fatty acid chains are associated with the risk of hemorrhagic stroke: a Mendelian randomization study

Background and objectiveHemorrhagic stroke, characterized by acute bleeding due to cerebrovascular lesions, is associated with plasma lipids and endothelial damage. The causal relationship between genetic plasma lipid levels and hemorrhagic stroke remains unclear. This study employs a two-sample Mendelian randomization (MR) analysis to explore the causal relationship between plasma lipid profiles with different fatty acid chains and the risk of intracerebral and subarachnoid hemorrhage, the two main subtypes of hemorrhagic stroke.MethodsThe datasets for exposure and outcome summary statistics were obtained from publicly available sources such as the GWAS Catalog, IEU OpenGWAS project, and FinnGen. The two-sample MR analysis was employed to initially assess the causal relationship between 179 plasma lipid species and the risk of intracerebral and subarachnoid hemorrhage in the Finnish population, leading to the identification of candidate lipids. The same methods were applied to reanalyze data from European populations and conduct a meta-analysis of the candidate lipids. The Inverse Variance Weighting (IVW) method served as the primary analysis for causal inference, with additional methods used for complementary analyses. Sensitivity analysis was conducted to clarify causal relationships and reduce biases.ResultsTwo analyses using Mendelian randomization were performed, followed by meta-analyses of the results. A causal relationship was established between 11 specific lipid species and the occurrence of intracerebral hemorrhage within the European population. Additionally, 5 distinct lipid species were associated with subarachnoid hemorrhage. Predominantly, lipids with linoleic acid and arachidonic acid side chains were identified. Notably, lipids containing arachidonic acid chains (C20:4) such as PC 18:1;0_20:4;0 consistently showed a decreased risk of both intracerebral hemorrhage [p &amp;lt; 0.001; OR(95% CI) = 0.892(0.835–0.954)] and subarachnoid hemorrhage [p = 0.002; OR(95% CI) = 0.794(0.689–0.916)]. Conversely, lipids with linoleic acid chains (C18:2) were associated with an increased risk of intracerebral hemorrhage.ConclusionThis study identifies a potential causal relationship between lipids with different fatty acid side chains and the risk of intracerebral and subarachnoid hemorrhagic stroke, improving the understanding of the mechanisms behind the onset and progression of hemorrhagic stroke.

Assessing the genetic associations between plasma lipidomic profiles and psoriasis vulgaris.

Several studies have indicated a potential causal relationship between plasma standard lipids, such as high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), triglycerides (TG), and total cholesterol (TC), and psoriasis. However, few studies have offered causal evidence of lipid species beyond these standard lipids. We conducted an analysis using a genome-wide association study (GWAS) dataset comprising 179 lipid species, including 13 types across four major categories, to identify instrumental variables (IVs) associated with plasma lipids. We utilized two GWAS datasets from the IEU and Finngen for psoriasis vulgaris as the outcome. A two-sample Mendelian randomization (MR) analysis was used to explore the causal relationship between 179 lipid species and psoriasis vulgaris in two datasets. Lipid species showing causal association in both psoriasis datasets were compared for overlap. Our study identified potential causal relationships between six lipid species and psoriasis vulgaris: phosphatidylcholine (16:1_18:2), phosphatidylcholine (18:0_18:2), phosphatidylcholine (18:1_20:4), phosphatidylethanolamine (16:0_18:2), phosphatidylinositol (18:0_20:3), and triacylglycerol (50:1). In summary, elevated plasma levels of phosphatidylcholine (16:1_18:2), phosphatidylcholine (18:0_18:2), phosphatidylethanolamine (16:0_18:2), phosphatidylinositol (18:0_20:3), and triacylglycerol (50:1) may increase the risk of psoriasis vulgaris. Conversely, plasma phosphatidylcholine (18:1_20:4) may play a protective role against psoriasis vulgaris.

Investigation of the causal relationship between breast cancer and thyroid cancer: a set of two-sample bidirectional Mendelian randomization study.

A potential association between breast (BC) and thyroid cancer (TC) has been observed. We investigated if the relationship between BC and TC is causal using bidirectional Mendelian randomization (MR) in Asian and European populations. BC-linked single nucleotide polymorphisms (SNPs) were acquired from a genome-wide association study (GWAS) conducted by the Breast Cancer Association Consortium and Biobank Japan. The most recent TC GWAS data were obtained from the FinnGen Project and National Biobank of Korea. We assessed the potential causal relationship between BC and TC using various MR methods, including inverse-variance-weighting (IVW). Sensitivity, heterogeneity, and pleiotropic tests were performed to assess reliability. We found a bidirectional causal association between BC and TC within Europeans (IVW, TC on BC: odds ratio [OR] 1.090, 95% confidence interval [CI]: 1.012-1.173, P = 0.023; BC on TC: OR 1.265, 95% CI: 1.158-1.381, P < 0.001). A one-way causal relationship between BC susceptibility and TC risk was found in Asians (IVW BC on TC: OR 2.274, 95% CI: 2.089-2.475, P < 0.001). Subsequently, we identified a noteworthy bidirectional causal relationship between estrogen receptor (ER)-positive BC and TC (IVW, TC on ER-positive BC: OR 1.104, 95% CI: 1.001-1.212, P = 0.038; ER-positive BC on TC: OR 1.223, 95%CI: 1.072-1.395, P = 0.003), but not ER-negative BC and TC in Europeans. We revealed a reciprocal causal association between ER-positive BC and TC. These findings establish a theoretical framework for the simultaneous surveillance and treatment of BC and TC.

COVID-19 and the risk of acute cardiovascular diseases: a two-sample Mendelian randomization study

BackgroundEvidence suggests that coronavirus disease 2019 (COVID-19) is associated with the risk of cardiovascular diseases (CVDs). However, the results are inconsistent, and the causality remains to be established. We aimed to investigate the potential causal relationship between COVID-19 and CVDs by using two-sample Mendelian randomization (MR) analysis.MethodsSummary‐level data for COVID-19 and CVDs including myocarditis, heart failure (HF), acute myocardial infarction (AMI), arrhythmia and venous thromboembolism (VTE) were obtained from the IEU OpenGWAS project, a public genome-wide association study (GWAS). Single nucleotide polymorphisms (SNPs) were used as instrumental variables. Five complementary MR methods were performed, including inverse variance weighted (IVW), MR-Egger, weighted median, weighted mode and simple mode methods. IVW method was considered as the primary approach. Besides, sensitivity analyses, including Cochran’s Q test, MR-Egger intercept test, and leave-one-out analysis, were performed to evaluate the robustness of the results.ResultsAccording to the IVW results, our MR study indicated that genetically predicted COVID-19 was not causally connected with the risk of CVDs [myocarditis: odds ratio (OR) = 1.407, 95% confidence interval (CI) = 0.761-2.602, p-value = 0.277; HF: OR = 1.180, 95% CI = 0.980-1.420, p-value = 0.080; AMI: OR = 1.002, 95% CI = 0.998-1.005, p-value = 0.241; arrhythmia: OR = 0.865, 95% CI = 0.717-1.044, p-value = 0.132; VTE: OR = 1.013, 95% CI = 0.997-1.028, p-value = 0.115]. The supplementary MR methods showed similar results. Sensitivity analyses suggested that the causal estimates were robust.ConclusionThis two-sample MR analysis did not provide sufficient evidence for a causal relationship between COVID-19 and the risk of acute CVDs, which may provide new insights into the prevention of acute CVDs in COVID-19 patients.

Exploring the causal role of immune cells in vascular dementia: A bidirectional mendelian randomization study

BackgroundThe aim of this study was to explore the causal association between immune cells and VaD based on a two-sample bidirectional Mendelian randomization study. MethodsBidirectional two-sample MR analyses based on pooled datasets from publicly available genome-wide association studies were performed using inverse variance weighted (IVW), weighted median (WE), and MR–Egger regressions to evaluate the causal relationships between immune cells and vascular dementia. Heterogeneity was assessed using Cochran's Q statistic. The reliability of the MR analysis results was verified by using the MR-PRESSO method for outlier detection, the MR–Egger method for horizontal multivariate analysis, and the leave-one-out method for sensitivity analysis. ResultsSpecifically, 27 immunophenotypes were associated with VaD pathogenesis, including Sw mem %lymphocyte (P = 0.043), CD38 on CD20- (P = 0.039), CD11c+ monocyte AC (P = 0.024), DC AC (P = 0.002), CCR2 on CD62L+ myeloid DC (P = 0.039), Resting Treg %CD4 (P = 0.042), Activated & resting Treg %CD4+ (P = 0.038), CD28+ CD45RA− CD8br %CD8br (P = 0.047), NK %CD3− lymphocyte (P = 0.042), CD45 on B cell (P = 0.029), FSC-A on NKT (P = 0.033), CD45 on CD33br HLA DR+ CD14− (P = 0.039) were significantly correlated with increased VaD risk. Additionally, four immune phenotypes, namely, CD19 on CD20−, Resting Treg %CD4, Activated & resting Treg %CD4+, and CD11c+ monocyte AC, showed bidirectional effects on VaD. ConclusionsMR analysis revealed potential causal relationships between certain immune cells and VaD. Our preliminary exploration through immune cell infiltration analysis highlights the significant value of immune cells in VaD. Therefore, this study may provide a new perspective for the prevention and treatment of VaD.

A Mendelian randomization study investigating causal links between gut microbiota or metabolites and chronic hepatitis B

ObjectiveThis study aimed to explore the potential causal relationship between the gut microbiota and/or its metabolites and the progression of chronic hepatitis B (CHB).MethodThe gut microbiota was used as the exposure factor. The training set exposure data were obtained from the China Nucleotide Sequence Archive (CNSA). Genome-wide association study (GWAS) data from Asia were used as the outcome variables. Outcome data for both the training and validation sets were sourced from the GWAS Catalog database. A dual-sample Mendelian randomization approach was used to analyze the causal relationships, with the inverse variance-weighted method serving as the main analytical strategy. Sensitivity analysis was conducted to assess the robustness of Mendelian randomization analysis results.ResultIn the training set database, analysis using the inverse variance-weighted method revealed a positive correlation between Fusobacterium varium and chronic hepatitis B [OR = 1.122, 95% CI (1.016, 1.240), p = 0.022]. Conversely, Veillonella parvula exhibited a negative correlation with chronic hepatitis B [OR = 0.917, 95% CI (0.852, 0.987), p = 0.021]. Sensitivity analysis revealed no evidence of pleiotropy and heterogeneity. No gut microbiota metabolites with a causal effect on chronic hepatitis B were identified. Additionally, no associations between the gut microbiota and the progression of chronic hepatitis B were found in the validation data from the European cohort.ConclusionThis study suggests that F. varium may facilitate the progression of chronic hepatitis B, whereas V. parvula may impede it. No causal relationships between gut microbiota metabolites and chronic hepatitis B were established.

The causal association between inflammatory bowel disease and breast cancer: a bidirectional two-sample Mendelian randomization study

Objective: This Mendelian Randomization (MR) study aims to explore the potential bidirectional causal relationship between Inflammatory Bowel Disease (IBD) and Breast Cancer (BC).Materials and Methods: We utilized genetic instruments from the summary statistics of genome-wide association studies (GWAS) on IBD among individuals of European ancestry (12,882 cases and 21,770 controls) to investigate the association with breast cancer (14,910 cases and 17,588 controls) and vice versa. The primary causal estimates were obtained using the Inverse Variance Weighting Method (IVW), and the robustness of the results was evaluated through a series of sensitivity analyses.Results: The study found a positive impact of genetically predicted IBD on breast cancer (OR = 1.047; 95% CI:1.009–1.087; p = 0.014); in the analysis of IBD subtypes, genetically predicted Crohn’s Disease (CD) also had a positive effect on breast cancer (OR = 1.044; 95% CI:1.015–1.073; p = 0.002), but genetically predicted Ulcerative Colitis (UC) did not show a significant effect on breast cancer (p &amp;gt; 0.05). The reverse Mendelian Randomization analysis indicated that genetically predicted breast cancer promoted the overall occurrence of IBD (OR = 1.112; 95% CI:1.022–1.211; p = 0.014); however, genetically predicted breast cancer did not show a significant correlation with IBD subtypes (CD and UC) (p &amp;gt; 0.05). Genetic predictions indicate a positive effect of Crohn’s Disease (CD) on the risk of Estrogen Receptor-Positive Breast Cancer (ER + BC), with (OR = 1.021; 95% CI:1.002–1.040; p = 0.002). Furthermore, a reverse Mendelian randomization analysis reveals that genetically predicted ER + BC contributes to the increased incidence of ulcerative colitis (UC), as indicated by (OR = 1.098; 95% CI:1.032–1.168; p = 0.003). In contrast, genetically predicted Estrogen Receptor-Negative Breast Cancer (ER-BC) has been shown to promote the overall occurrence of inflammatory bowel disease (IBD), with (OR = 1.153; 95% CI:1.008–1.319; p = 0.037). However, bidirectional two-sample Mendelian randomization analyses between other pairs did not reveal any significant associations (p &amp;gt; 0.05).Conclusion: This study elucidates the bidirectional causal association between breast cancer and inflammatory bowel disease, highlighting the necessity of screening for IBD in breast cancer patients and for breast cancer in IBD patients in clinical settings.

Potential causal association between serum vitamin D levels and intervertebral disc degeneration: A mendelian randomization study

ObjectivesIntervertebral disc degeneration (IDD) is a prevalent musculoskeletal disorder with substantial implications for disability and healthcare expenditures. The role of serum vitamin D (25-Hydroxyvitamin D, 25(OH)D) levels in the pathogenesis of various musculoskeletal conditions has been explored in prior observational studies, suggesting a potential association. While previous observational studies have suggested an association between the two conditions, it might confound the effect of 25(OH)D on IDD. This Mendelian randomization (MR) study seeks to elucidate the causal relationship between 25(OH)D and IDD. MethodsWe performed a MR analysis using summary-level data from genome-wide association studies (GWAS) of 25(OH)D (sample size = 441,291 European) and IDD (sample size = 336,439 (cases = 41,669, controls = 294,770) European). Single nucleotide polymorphisms (SNPs) significantly associated with 25(OH)D (p < 5 × 10−8) were selected as instrumental variables. The associations between genetically predicted 25(OH)D and IDD were estimated using the inverse-variance weighted (IVW) method, with sensitivity analyses employing the weighted median, MR-Egger, and MR-PRESSO approaches to assess the robustness of the findings. ResultsIn the primary IVW analysis, genetically predicted 25(OH)D was unrelated associated with IDD (odds ratio (OR) = 0.9671, 95% confidence interval (CI): 0.8956–1.0444, p = 0.39). The results remained consistent across the sensitivity analyses, and no significant directional pleiotropy was detected (MR-Egger intercept: p = 0.64). ConclusionsThis study found no obvious evidence that 25(OH)D is causally associated with IDD risks. We call for larger sample size studies to further unravel the potential causal relationship and the exact mechanism.

Causal association between triglycerides and cholesterol-lowering medication with non-rheumatic valve disease: A 2-sample Mendelian randomization study.

Previous studies have found a possible causal relationship between triglycerides and lipid-lowering drugs and valvular disease. The aim of this study was to explore the potential causal relationship between triglycerides and lipid-lowering drugs and valvular disease using Mendelian randomization (MR) analysis. Data sets associated with triglycerides (441,016 participants and 12,321,875 single nucleotide polymorphisms [SNPs]) and cholesterol-lowering drugs (209,638 participants and 9851,867 SNPs) were retrieved from the Genome-Wide Association Study (GWAS) database. A total of 297 and 49 SNPs significantly associated with triglycerides and cholesterol-lowering drugs, respectively (P < 5 × 10-8), were identified. Similarly, data sets for non-rheumatic valve diseases (NVDs) (361,194 participants and 10,080,950 SNPs) were obtained from the GWAS database. Inverse variance weighting was used as the primary method for calculating the odds ratio (OR) and 95% confidence intervals (CI). The MR-Egger, weighted median, and weighted mode analyses were also used to test the robustness of the main results. The MR-Egger intercept test and the MR-PRESSO test were used to evaluate horizontal pleiotropy. Inverse variance weighted (IVW) results showed that both triglyceride and cholesterol-lowering medication were positively associated with NVDs (OR = 1.001, 95% CI 1.000-1.0012, P = 0.006; OR = 1.007, 95% CI 1.003-1.010; P = 0.002). This study suggests that both triglyceride and cholesterol-lowering medications are positively associated with NVDs, suggesting that lowering triglyceride levels or the use of cholesterol-lowering medications may reduce the incidence of NVDs. However, larger samples are required for further validation.

Causal association between skin cancer and immune cells: mendelian randomization (MR) study

BackgroundNumerous meta-analyses and clinical studies have shown that subtypes of immune cells are associated with the development of skin cancer, but it is not clear whether this association is causal or biased. Mendelian randomization (MR) analysis reduces the effect of confounding factors and improves the accuracy of the results when compared to traditional studies. Thus, in order to examine the causal relationship between various immune cell and skin cancer, this study employs two-sample MR.MethodsThis study assesses the causal association between 731 immune cell characteristics and skin cancer using a two-sample Mendel randomization (MR) methodology. Multiple MR methods were used to bias and to derive reliable estimates of causality between instrumental variables and outcomes. Comprehensive sensitivity analyses were used to validate the stability, heterogeneity and horizontal multiplicity of the results.ResultsWe discovered that potential causal relationships between different types of immune cells and skin cancer disease. Specifically, one type of immune cell as potentially causal to malignant melanoma of skin (MM), eight different types of immune cells as potentially causal to basal cell carcinoma (BCC), four different types of immune cells as potentially causal to actinic keratosis (AK), and no different types of immune cells were found to have a potential causal association with squamous cell carcinoma(SCC), with stability in all of the results.ConclusionThis study demonstrates the close connection between immune cells and skin cancer disease by genetic means, which enriches the current knowledge about the role of immune cells in skin cancer and also contributes to the design of therapeutic strategies from an immunological perspective.

Dissecting the mediating role of cytokines in the interaction between immune traits and sepsis: insights from comprehensive mendelian randomization.

Sepsis is a life-threatening organ dysfunction resulting from a dysregulated host response to infection, yet the potential causal relationship between the immunophenotype and sepsis remains unclear. Genetic variants associated with the immunophenotype served as instrumental variables (IVs) in Mendelian randomization (MR) to elucidate the causal impact of the immunophenotype on three sepsis outcomes. Additionally, a two-step MR analysis was conducted to identify significant potential mediators between the immunophenotype and three sepsis outcomes. Our MR analysis demonstrated a significant association between the immunophenotype and sepsis outcome, with 36, 36, and 45 the immunophenotype associated with the susceptibility, severity, and mortality of sepsis, respectively. Specifically, our analysis highlighted the CD14+ CD16+ monocyte phenotype as a significant factor across all three sepsis outcomes, with odds ratios (ORs) and corresponding confidence intervals (CIs) indicating its impact on sepsis (OR = 1.047, CI: 1.001-1.096), sepsis in Critical Care Units (OR = 1.139, CI: 1.014-1.279), and sepsis-related 28-day mortality (OR = 1.218, CI: 1.104-1.334). Mediation analyses identified seven cytokines as significant mediators among 91 potential cytokines, including interleukin-5 (IL-5), S100A12, TNF-related apoptosis-inducing ligand (TRAIL), T-cell surface glycoprotein CD6 isoform, cystatin D, interleukin-18 (IL-18), and urokinase-type plasminogen activator (uPA). Furthermore, reverse MR analysis revealed no causal effect of sepsis outcomes on the immunophenotype. Our MR study suggests that the immunophenotype is significantly associated with the susceptibility, severity, and mortality of patient with sepsis, providing, for the first time, robust evidence of significant associations between immune traits and their potential risks. This information is invaluable for clinicians and patients in making informed decisions and merits further attention.

Gut microbiota, plasma metabolites, and osteoporosis: unraveling links via Mendelian randomization.

Osteoporosis, characterized by reduced bone density and heightened fracture risk, is influenced by genetic and environmental factors. This study investigates the interplay between gut microbiota, plasma metabolomics, and osteoporosis, identifying potential causal relationships mediated by plasma metabolites. Utilizing aggregated genome-wide association studies (GWAS) data, a comprehensive two-sample Mendelian Randomization (MR) analysis was performed involving 196 gut microbiota taxa, 1,400 plasma metabolites, and osteoporosis indicators. Causal relationships between gut microbiota, plasma metabolites, and osteoporosis were explored. The MR analyses revealed ten gut microbiota taxa associated with osteoporosis, with five taxa positively linked to increased risk and five negatively associated. Additionally, 96 plasma metabolites exhibited potential causal relationships with osteoporosis, with 49 showing positive associations and 47 displaying negative associations. Mediation analyses identified six causal pathways connecting gut microbiota to osteoporosis through ten mediating relationships involving seven distinct plasma metabolites, two of which demonstrated suppression effects. This study provides suggestive evidence of genetic correlations and causal links between gut microbiota, plasma metabolites, and osteoporosis. The findings underscore the complex, multifactorial nature of osteoporosis and suggest the potential of gut microbiota and plasma metabolite profiles as biomarkers or therapeutic targets in the management of osteoporosis.

Gut microbiota linked to hydrocephalus through inflammatory factors: a Mendelian randomization study.

The gut microbiota (GM) has been implicated in neurological disorders, but the relationship with hydrocephalus, especially the underlying mechanistic pathways, is unclear. Using Mendelian randomization (MR), we aim to discover the mediating role of inflammatory factors in the relationship between GM and hydrocephalus. After removing confounders, univariable and multivariable MR analyses were performed using summary statistics to assess the causal relationships between GM, inflammatory factors (IL-17A and IL-27), and types of hydrocephalus. Meta-analyses were used to reconcile the differences in MR results between different hydrocephalus sources. Finally, mediator MR analyses were applied to determine the mediating effect of inflammatory factors. Various sensitivity analysis methods were employed to ensure the reliability and stability of the results. After correction for P-values, Firmicutes (phylum) (OR, 0.34; 95%CI, 0.17-0.69; P = 2.71E-03, P FDR = 2.44E-02) significantly reduced the risk of obstructive hydrocephalus. The remaining 18 different taxa of GM had potential causal relationships for different types of hydrocephalus. In addition, Firmicutes (phylum) decreased the risk of obstructive hydrocephalus by increasing levels of IL-17A (mediating effect = 21.01%), while Eubacterium ruminantium group (genus) increased the risk of normal-pressure hydrocephalus by decreasing levels of IL-27 (mediating effect = 7.48%). We reveal the connection between GM, inflammatory factors (IL-17A and IL-27), and hydrocephalus, which lays the foundation for unraveling the mechanism between GM and hydrocephalus.

Causal relationship between C-reactive protein and ischemic stroke caused by atherosclerosis: A Mendelian randomization study

ObjectivesThis study investigates the association between C-reactive protein (CRP) and ischemic stroke caused by large artery atherosclerosis (LAA). MethodsFive Mendelian Randomization (MR) methodologies were used for two-sample analyses: Inverse Variance Weighting (IVW), MR-Egger regression, Weighted Median (WM), Simple Mode, and Weighted Mode. CRP exposure data were obtained from aggregated summary statistics from a meta-analysis of genome-wide association studies (GWAS) in individuals of European ancestry (n = 343,524; UK Biobank). Stroke data were used as the outcome, with specific dataset details for relevant subtypes (cases = 40,585, controls = 406,111). ResultsIn the CRP GWAS dataset, selected single nucleotide polymorphisms (SNPs) as instrumental variables (IVs) showed genome-wide significance and a causal relationship with CRP, particularly in relation to LAA stroke. IVW indicated a robust causal connection between CRP and LAA stroke (Beta = 0.151, SE = 0.055, P = 0.006). The WM approach supported this relationship (Beta = 0.176, SE = 0.082, P = 0.033). However, MR-Egger regression suggested a potential absence of a causal link (Beta = 0.098, SE = 0.077, P = 0.206), with minimal influence from horizontal pleiotropy (Intercept = 0.0029; P = 0.317). The Simple mode found no significant association (Beta = 0.046, SE = 0.217, P = 0.834), while the Weighted mode revealed a significant causal association (Beta = 0.138, SE = 0.059, P = 0.020) between CRP and LAA stroke. ConclusionsMR analysis provides evidence for a potential causal relationship between CRP and an increased risk of LAA stroke.

Type 2 Diabetes, Circulating Metabolites, and Calcific Aortic Valve Stenosis: A Mendelian Randomization Study.

Epidemiological studies have shown an association between type 2 diabetes (T2D) and calcific aortic valve stenosis (CAVS), but the potential causal relationship and underlying mechanisms remain unclear. Therefore, we conducted a two-sample and two-step Mendelian randomization (MR) analysis to evaluate the association of T2D with CAVS and the mediating effects of circulating metabolites and blood pressure using genome-wide association study (GWAS) summary statistics. The inverse variance weighted (IVW) method was used for the primary MR analysis, and comprehensive sensitivity analyses were performed to validate the robustness of the results. Our results showed that genetically predicted T2D was associated with increased CAVS risk (OR 1.153, 95% CI 1.096-1.214, p < 0.001), and this association persisted even after adjusting for adiposity traits in multivariable MR analysis. Furthermore, the two-step MR analysis identified 69 of 251 candidate mediators that partially mediated the effect of T2D on CAVS, including total branched-chain amino acids (proportion mediated: 23.29%), valine (17.78%), tyrosine (9.68%), systolic blood pressure (8.72%), the triglyceride group (6.07-11.99%), the fatty acid group (4.78-12.82%), and the cholesterol group (3.64-11.56%). This MR study elucidated the causal impact of T2D on CAVS risk independently of adiposity and identified potential mediators in this association pathways. Our findings shed light on the pathogenesis of CAVS and suggest additional targets for the prevention and intervention of CAVS attributed to T2D.

Association between serum total cholesterol and the development of gastric cancer: A two-way two-sample Mendelian randomization study.

Previous epidemiologic studies have suggested a potential negative correlation between total cholesterol (TC) and Gastric cancer (GC); however, several observational studies have shown conflicting results and have failed to provide definitive evidence for a causal relationship between TC and GC. Therefore, we conducted a 2-sample bidirectional Mendelian randomization (MR) study to explore the genetic correlation and potential causal relationship between the 2 variables. We screened for single nucleotide polymorphisms (SNPs) associated with TC and GC utilizing a large-scale genome-wide association study (GWAS) public database. The causal relationship was analyzed using 5 MR analysis methods: inverse variance weighting (IVW), weighted median, MR-Egger regression, weighted mode, and simple mode. Additionally, reverse MR analysis was performed to evaluate the possibility of reverse causality. Sensitivity analyses were conducted, including heterogeneity tests, horizontal multiple validity tests, and leave-one-out tests. After meticulous screening, 79 SNPs were identified as instrumental variables (IVs). The IVW method revealed a causal relationship between TC and GC (OR = 0.844; 95% CI: 0.741-0.961; P = .01). Sensitivity analyses did not detect significant horizontal pleiotropy. Though heterogeneity was observed in the forward MR analysis (IVW, Qp = 0.0006), the results remained reliable as we utilized the IVW random-effects model as the primary analytical method. Furthermore, inverse MR analysis found no evidence of reverse causality between TC and GC, effectively ruling out the influence of GC on the reverse causality of TC. Our MR study provided evidence of a causal association between TC and GC, suggesting that TC acts as a protective factor against GC due to its negative association with the disease.