The causal relationship between allergic diseases and heart failure: Evidence from Mendelian randomization study

Mendelian Randomization Analysis Reveals the Causal Relationships Between Autoimmune Diseases and Idiopathic Thrombocytopenic Purpura and the Mediating Role of Immune Cells

Background

Idiopathic thrombocytopenic purpura (ITP) is related to multiple autoimmune diseases clinically, yet the causal relationship remains unclear. This study employed Mendelian randomization (MR) to explore the genetic causal relationship between autoimmune diseases and ITP and potential mediators in the European population.

Methods

Summary statistics of 10 common autoimmune diseases and ITP were extracted for analysis. Bidirectional two-sample MR and two-step MR were conducted.

Results

Multiple sclerosis (MS, inverse variance weighted [IVW]: odds ratio (OR)=5.840E+16, false discovery rate (FDR)=0.049), celiac disease (CeD, IVW: OR=1.173, FDR=0.023), systemic lupus erythematosus (SLE, IVW: OR=1.068, FDR=0.049), and autoimmune hyperthyroidism (AIH, IVW: OR=1.265, FDR=0.037) are risk factors for ITP. Rheumatoid arthritis (RA, IVW: OR=1.112, FDR=0.055) may be a potential risk factor. Crohn's disease (CD, IVW: OR=0.816, FDR=0.049), ulcerative colitis (UC, IVW: OR=0.709, FDR=0.042), and psoriasis (PsO, IVW: OR=1.690E - 04, FDR=0.042) are protective factors. No clear causal relationship between ankylosing spondylitis (AS, IVW: OR=1.016, FDR=0.553) and type 1 diabetes mellitus (T1DM, IVW: OR=1.035, FDR=0.577) and ITP. Immune cells act as mediators between CeD and ITP and CD and ITP.

Conclusion

This study clarified the relationship between some autoimmune diseases and ITP and the mediating role of immune cells.

Analysis of shared pathogenic mechanisms and drug targets in myocardial infarction and gastric cancer based on transcriptomics and machine learning

Background

Recent studies have suggested a potential association between gastric cancer (GC) and myocardial infarction (MI), with shared pathogenic factors. This study aimed to identify these common factors and potential pharmacologic targets.

Methods

Data from the IEU Open GWAS project were used. Two-sample Mendelian randomization (MR) analysis was used to explore the causal link between MI and GC. Transcriptome analysis identified common differentially expressed genes, followed by enrichment analysis. Drug target MR analysis and eQTLs validated these associations with GC, and the Steiger direction test confirmed their direction. The random forest and Lasso algorithms were used to identify genes with diagnostic value, leading to nomogram construction. The performance of the model was evaluated via ROC, calibration, and decision curves. Correlations between diagnostic genes and immune cell infiltration were analyzed.

Results

MI was linked to increased GC risk (OR=1.112, P=0.04). Seventy-four genes, which are related mainly to ubiquitin-dependent proteasome pathways, were commonly differentially expressed between MI and GC. Nine genes were consistently associated with GC, and eight had diagnostic value. The nomogram built on these eight genes had strong predictive performance (AUC=0.950, validation set AUC=0.957). Immune cell infiltration analysis revealed significant correlations between several genes and immune cells, such as T cells, macrophages, neutrophils, B cells, and dendritic cells.

Conclusion

MI is associated with an increased risk of developing GC, and both share common pathogenic factors. The nomogram constructed based on 8 genes with diagnostic value had good predictive performance.

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

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

Mendelian Randomization Studies in Atopic Dermatitis: A Systematic Review

Prior studies have found associations between atopic dermatitis (AD) and comorbidities, including depression, obesity, asthma, and allergic rhinitis. Although observational studies often cannot establish robust causality between potential risk factors and AD, Mendelian randomization minimizes confounding when exploring causality by relying on random allelic assortment at birth. In this study, we systematically reviewed 30 Mendelian randomization studies in AD. Body mass index, gut microbial flora, the IL-18 signaling pathway, and gastroesophageal reflux disease were among the causal factors for AD, whereas AD was causal for several medical conditions, including heart failure, rheumatoid arthritis, and conjunctivitis. These insights may improve preventive counseling in AD.

Causal role of immune cells in psoriasis: a Mendelian randomization analysis

Background

A growing body of evidence has shown that immune cells are linked to psoriasis. It is, however, still unclear if these associations reflect a relationship of cause and effect.

Objective

We employed a two-sample Mendelian randomization (MR)-based study to elucidate the probable causative connection between immune cells and psoriasis.

Methods

Summary information for psoriasis (Ncase = 5,427, Ncontrol = 479,171) was obtained from the European Bioinformatics Institute. Summarized statistical information on 731 immune cell features, including morphological parameters (MP; n = 32), relative cell number (n = 192), median fluorescence intensity (MFI) of surface antigens (n = 389), and absolute cell number (n = 118), was obtained from the genome-wide association studies (GWAS) catalog. The research consisted of forward MR analysis, in which immune cell traits were used as the exposure factor, and psoriasis was the outcome, as well as reverse MR analysis, in which psoriasis was used as the exposure factor, and immune cell traits were the outcome. We ran numerous sensitivity analyses to ascertain the study results for robustness, heterogeneity, and potential multiple-biological effects.

Result

This research determined a probable causative connection between immune cells and psoriasis. In particular, we identified 36 distinct types of immune cells that are potentially causally linked to psoriasis.

Conclusion

Our findings indicate strong causal correlations between 36 immunological phenotypes and psoriasis, thus, directing future clinical trials.

Unraveling the causal role of immune cells in gastrointestinal tract cancers: insights from a Mendelian randomization study

Background

Despite early attempts, the relationship between immune characteristics and gastrointestinal tract cancers remains incompletely elucidated. Hence, rigorous and further investigations in this domain hold significant clinical relevance for the development of novel potential immunotherapeutic targets.

Methods

We conducted a two-sample Mendelian randomization (MR) analysis using the tools available in the "TwoSampleMR" R package. The GWAS data for these 731 immune traits were sourced from the GWAS Catalog database. Concurrently, data on gastrointestinal tract cancers, encompassing malignant tumors in the esophagus, stomach, small intestine, colon, and rectum, were extracted from the FinnGen database. The immune traits subjected to MR analysis predominantly fall into four categories: median fluorescence intensities (MFI), relative cell (RC), absolute cell (AC), and morphological parameters (MP). To ensure the reliability of our findings, sensitivity analyses were implemented to address robustness, account for heterogeneity, and alleviate the impact of horizontal pleiotropy.

Results

A total of 78 immune traits causally linked to gastrointestinal tract cancers were identified, encompassing esophageal cancer (12 traits), gastric cancer (13 traits), small intestine cancer (22 traits), colon cancer (12 traits), and rectal cancer (19 traits). Additionally, 60 immune traits were recognized as protective factors associated with gastrointestinal tract cancers, distributed across esophageal cancer (14 traits), gastric cancer (16 traits), small intestine cancer (7 traits), colon cancer (14 traits), and rectal cancer (9 traits). Furthermore, it was observed that seven immune traits are causally related to gastrointestinal tract cancers in at least two locations. These traits include "CCR2 on CD14- CD16+ monocyte," "CD19 on IgD+ CD38-," "CD19 on IgD+ CD38- naive," "CD25hi CD45RA+ CD4 not Treg AC," "CD27 on unsw mem," "CD28 on CD39+ activated Treg," and "CD45 on CD4+."

Conclusion

This study elucidates a causal link between immune cells and gastrointestinal tract cancers at various sites through genetic investigation. The findings of this research open up new perspectives and resources for exploring tumor prevention strategies and immunotherapeutic targets.

Exploring the genetic association of allergic diseases with cardiovascular diseases: a bidirectional Mendelian randomization study

Background

In observational and experimental studies, allergic diseases (AD) have been reported to be associated with some types of cardiovascular diseases (CVD), as both share common pathophysiological processes involving inflammation and metabolic disorders. However, the direction of the causal association between them remains unclear. This Mendelian randomization (MR) study aims to examine the bidirectional causality between AD and CVD.

Methods

We utilized publicly available genome-wide association study (GWAS) summary statistics data from European participants in the UK Biobank and the IEU Open GWAS database. Genetic variants associated with AD, asthma, and CVD were identified and used as instrumental variables to investigate the genetically causal association between them. MR analyses were performed using various analytical methods, including inverse variance weighted-fixed effects (IVW-FE), inverse variance weighted-multiplicative random effects (IVW-RE), MR-Egger, weighted median, weighted mode, and maximum likelihood. Sensitivity tests were conducted to assess the validity of the causality.

Results

The MR analysis with the IVW method revealed a genetically predicted association between AD and essential hypertension [odds ratio (OR)=0.9987, 95% confidence interval (CI): 0.9976-0.9998, P=0.024], as well as between asthma and atrial fibrillation (OR=1.001, 95% CI: 1.0004-1.0017, P=6.43E-05). In the reverse MR analyses, heart failure was associated with allergic diseases (OR=0.0045, 95% CI: 1.1890E-04 - 0.1695, P=0.004), while atherosclerosis (OR=8.7371E-08, 95% CI: 1.8794E-14 - 4.0617E-01, P=0.038) and aortic aneurysm and dissection (OR=1.7367E-07, 95% CI: 3.8390E-14 - 7.8567E-01, P=0.046) might be protective factors of asthma. However, after a Bonferroni correction, only the association between asthma and atrial fibrillation remained robust.

Conclusion

The MR study revealed that asthma is a predominant risk of atrial fibrillation in European individuals, consistent with most experimental and observational studies. Whether AD affects other CVD and the causality between them needs further investigation.