BACKGROUND: Asthma is associated with upper airway diseases and allergic diseases; however, the causal effects need to be investigated further. Thus, we performed this two-sample Mendelian randomization (MR) analysis to explore and measure the causal effects of asthma on allergic rhinitis (AR), vasomotor rhinitis (VMR), allergic conjunctivitis (AC), atopic dermatitis (AD), and allergic urticaria (AU).
METHODS: The data for asthma, AR, VMR, AC, AD, and AU were obtained from large-scale genome-wide association studies summarized recently. We defined single-nucleotide polymorphisms satisfying the MR assumptions as instrumental variables. Inverse-variance weighted (IVW) approach under random-effects was applied as the dominant method for causal estimation. The weighted median approach, MR-Egger regression analysis, MR pleiotropy residual sum and outlier test, and leave-one-out sensitivity analysis were performed as sensitivity analysis. Horizontal pleiotropy was measured using MR-Egger regression analysis. Significant causal effects were attempted for replication and meta-analysis.
RESULTS: We revealed that asthma had causal effects on AR (IVW, odds ratio [OR] = 1.93; 95% confidence interval [CI], 1.74-2.14; p < 0.001), VMR (IVW, OR = 1.40; 95% CI, 1.15-1.71; p < 0.001), AC (IVW, OR = 1.65; 95% CI, 1.49-1.82; p < 0.001), and AD (IVW, OR = 2.13; 95% CI, 1.82-2.49; p < 0.001). No causal effect of asthma on AU was observed. Sensitivity analysis further assured the robustness of these results. The evaluation of the replication stage and meta-analysis further confirmed the causal effect of asthma on AR (IVW OR = 1.81, 95% CI 1.62-2.02, p < 0.001), AC (IVW OR = 1.44, 95% CI 1.11-1.87, p < 0.001), and AD (IVW OR = 1.85, 95% CI 1.42-2.41, p < 0.001).
CONCLUSIONS: We revealed and quantified the causal effects of asthma on AR, VMR, AC, and AD. These findings can provide powerful causal evidence of asthma on upper airway diseases and allergic diseases, suggesting that the treatment of asthma should be a preventive and therapeutic strategy for AR, VMR, AC, and AD.

Rheumatoid arthritis (RA) is a common autoimmune disease, and some observational studies have indicated an association between Gastroesophageal Reflux Disease (GERD) and RA. However, the causal relationship between the two remains uncertain. We used Mendelian randomization (MR) to assess the causal relationship between GERD and RA. Two-sample Mendelian randomization analysis was performed using pooled data from large-scale genome-wide association studies. In addition, we performed multivariate MR analyses to exclude confounding factors between GERD and RA, including smoking quantity, drinking frequency, BMI, depression, and education attainment. The MR results for GERD on RA suggested a causal effect of the genetic susceptibility of GERD on RA (discovery dataset, IVW, odds ratio [OR] = 1.41, 95% confidence interval [CI] 1.22-1.63, p = 2.81 × 10-6; validation dataset, IVW, OR = 1.38, 95% CI 1.23-1.55, P = 1.76 × 10-8). Multivariate MR analysis also supports this result. But the results of the reverse MR analysis did not reveal compelling evidence that RA can increase the risk of developing GERD. Our bidirectional Two-Sample Mendelian randomization analysis and multivariate MR analysis provide support for the causal effect of GERD on RA. This discovery could offer new insights for the prevention and treatment of RA.

BACKGROUND: Previous observational studies have reported the correlation between circulating inflammatory cytokines and cerebral small vessel disease (CSVD). However, the causality of this association is uncertain. This study used Mendelian randomization to investigate the causal effect of circulating inflammatory cytokines on neuroimaging changes in CSVD.
METHODS: This study utilized genetic variances of 41 inflammatory cytokines and 3 neuroimaging markers of CSVD from genome-wide association studies to assess the causal effects in a two-sample Mendelian randomization approach. Inverse variance weighted analysis was used as the main analytical method, and sensitivity analysis was used to further validate the robustness of the results.
RESULTS: Increased IL-18 was associated with increased white matter hyperintensity (WMH) and mean diffusivity (MD) (β = 0.034, 95 % CI 0.002, 0.065, P=0.038, β = 0.157, 95 % CI 0.015, 0.299, P=0.030). However, increased IL-18 was associated with decreased fractional anisotropy (FA) (β = -0.141, 95 % CI -0.279, -0.002, P=0.047). Increased monocyte chemotactic protein-1(MCP-1) was associated with decreased FA (β = -0.278, 95 % CI -0.502, -0.054, P=0.015). Increased IL-10 levels and IL-2ra levels were associated with decreased risks of MD (β = -0.228, 95 % CI -0.448, -0.009, p = 0.041; β = -0.204, 95 % CI=-0.377, -0.031, p = 0.021).
CONCLUSIONS: This study revealed that increased levels of IL-18 and MCP-1 were associated with white matter microstructural injury, and increased levels of IL-10 and IL-2ra were associated with decreased MD.

UNASSIGNED: Observational studies have indicated that immune dysregulation in primary sclerosing cholangitis (PSC) primarily involves intestinal-derived immune cells. However, the causal relationship between peripheral blood immune cells and PSC remains insufficiently understood.
UNASSIGNED: A bidirectional two-sample Mendelian randomization (MR) analysis was implemented to determine the causal effect between PBC and 731 immune cells. All datasets were extracted from a publicly available genetic database. The standard inverse variance weighted (IVW) method was selected as the main method for the causality analysis. Cochran\'s Q statistics and MR-Egger intercept were performed to evaluate heterogeneity and pleiotropy.
UNASSIGNED: In forward MR analysis, the expression ratios of CD11c on CD62L+ myeloid DC (OR = 1.136, 95% CI = 1.032-1.250, p = 0.009) and CD62L-myeloid DC AC (OR = 1.267, 95% CI = 1.086-1.477, p = 0.003) were correlated with a higher risk of PSC. Each one standard deviation increase of CD28 on resting regulatory T cells (Treg) (OR = 0.724, 95% CI = 0.630-0.833, p < 0.001) and CD3 on secreting Treg (OR = 0.893, 95% CI = 0.823-0.969, p = 0.007) negatively associated with the risk of PSC. In reverse MR analysis, PSC was identified with a genetic causal effect on EM CD8+ T cell AC, CD8+ T cell AC, CD28- CD127- CD25++ CD8+ T cell AC, CD28- CD25++ CD8+ T cell AC, CD28- CD8+ T cell/CD8+ T cell, CD28- CD8+ T cell AC, and CD45 RA- CD28- CD8+ T cell AC.
UNASSIGNED: Our study indicated the evidence of causal effects between PSC and immune cells, which may provide a potential foundation for future diagnosis and treatment of PSC.

暂无摘要。

Previous observational studies have shown a bidirectional association between immune-mediated inflammatory disorders (IMID) and periodontal disease. However, evidence regarding the causal role of IMID and periodontal disease is still lacking. Therefore, we conducted a bidirectional two-sample Mendelian randomization (MR) study to uncover the potential genetic causal effects between IMID and periodontal disease.
Bidirectional two-sample MR analysis was employed. Data for ten IMIDs were sourced from genome-wide association studies (GWAS) conducted by the FinnGen Consortium (range from 1023 to 36321 cases) and UK Biobank (UKB) (range from 150 to 17574 cases). Furthermore, GWAS data for periodontal disease were obtained from the FinnGen Consortium (87497 cases), UKB (458 cases), and Gene Lifestyle Interactions in Dental Endpoints (GLIDE) consortium (17,353 periodontitis cases). Subsequently, the causal relationships were analyzed by random effects inverse variance weighting, weighted median, and MR-Egger. Sensitivity analyses were performed using the Cochrane Q test, funnel plot, and Mr-Egger intercept test to ensure robustness. Eventually, replication analysis and meta-analysis across different databases were carried out.
Systemic lupus erythematosus (SLE) [IVW: OR = 1.079 (95% CI: 1.032-1.128) and P < 0.001], Sjogren syndrome [IVW: OR = 1.082 (95% CI: 1.012-1.157) and P = 0.022] and hypothyroidism [IVW: OR = 1.52 (95% CI: 1.13-2.04) and P = 0.005] may increase the risk of periodontal disease. In addition, periodontal disease may reduce the risk of SLE [IVW: OR = 0.8079 (95% CI: 0.6764-0.9650) and P = 0.019] and hyperthyroidism [IVW: OR = 5.59*10-9 (95% CI: 1.43*10-15-2.18*10-2) and P = 0.014]. Meta-analysis indicated a causal correlation between SLE and an increased risk of periodontal disease: [OR = 1.08 (95% CI: 1.03-1.13), P = 0.0009]. No significant evidence suggests bilateral causal relationships between other IMIDs and periodontal disease. No significant estimation of heterogeneity or pleiotropy is detected.
Our study has confirmed a genetic causal relationship between IMIDs and periodontal disease, thereby unveiling novel potential mechanisms underlying IMIDs and periodontal disease. This discovery is promising in fostering interdisciplinary collaboration between clinicians and stomatologists to facilitate appropriate and precise screening, prevention, and early treatment of IMIDs and periodontal disease.

BACKGROUND: Maternal smoking during pregnancy disturbs fetal lung development, and induces in their offspring childhood respiratory diseases. Whether it has a continued impact on offspring adult lung health and exerts a casual effect of chronic respiratory diseases (CRDs), remains uncertain. We seek to determine the causal relationships between maternal smoking around birth and offspring adult CRDs, using summary data from previously described cohorts.
METHODS: Mendelian randomization (MR) study was used to analyze the genome-wide associations of maternal smoking around birth and offspring adult CRDs, including respiratory insufficiency, chronic obstructive pulmonary disease (COPD), related respiratory insufficiency, emphysema, COPD, COPD hospital admissions, early onset of COPD, later onset of COPD, asthma, idiopathic pulmonary fibrosis (IPF), lung cancer (LC), small cell lung carcinoma (SCLC), and lung squamous cell carcinoma (LUSC).
RESULTS: After removing single-nucleotide polymorphisms (SNPs) associated with smoking by the offspring, maternal smoking around birth was associated with increased risk of offspring adult respiratory diseases (OR=1.14; 95% CI: 1.013-1.284; p=0.030), respiratory insufficiency (OR=2.413; 95% CI: 1.039-5.603; p=0.040), COPD (OR=1.14; 95% CI: 1.013-1.284; p=0.003), and asthma (OR=1.336; 95% CI: 1.161-1.538; p<0.001). Besides, maternal smoking during pregnancy was associated with a greater risk of LUSC (OR=1.229; 95% CI: 0.992-1.523; p=0.059) than the risk of IPF (OR=1.001; 95% CI: 0.999-1.003; p=0.224), LC (OR=1.203; 95% CI: 0.964-1.501; p=0.103), or SCLC (OR=1.11; 95% CI: 0.77-1.601; p=0.577).
CONCLUSIONS: In this MR analysis, maternal smoking around birth caused a strong risk factor for the offspring to develop lung problems and CRDs in adulthood. The policy related to smoking cessation for mothers during pregnancy should be encouraged.

UNASSIGNED: Heart failure (HF) is a disease with numerous genetic and environmental factors that affect it. The results of previous studies indicated that immune phenotypes are associated with HF, but there have been inconclusive studies regarding a causal relationship. Therefore, Mendelian randomization (MR) analyses were undertaken to confirm the causal connections between immune phenotypes and HF, providing genetic evidence supporting the association of immune cell factors with HF risk.
UNASSIGNED: We selected instrumental variables that met the criteria based on data from the results of genome-wide association studies (GWAS) of immune phenotype and all-cause HF. An evaluation of the causal association between 731 immune cell factors and HF risk was carried out using the inverse variance weighted (IVW), MR-Egger regression (MR-Egger), and weighted median (WM) analysis methods. To determine the horizontal pleiotropy, heterogeneity, and stability of the genetic variants, the MR-Egger intercept test, Cochran\'s Q test, MR-PRESSO, and leave-one-out sensitivity analysis were performed.
UNASSIGNED: MR principal method (IVW) analysis showed that a total of 38 immune cell-related factors were significantly causally associated with HF. Further analyses combining three methods (IVW, MR-Egger and WME) showed that six exposure factors significantly associated with heart failure, as shown below. The effect of Dendritic cell Absolute Count, CD62l- CD86+ myeloid Dendritic cell Absolute Count, CD62l- CD86+ myeloid Dendritic cell% Dendritic cell, CD39+ CD8+ T cell% CD8+ T cell, CD3 on Central Memory CD4+ T cell on heart failure was positive. Whereas, a reverse effect was observed for CD14+ CD16+ monocyte% monocyte.
UNASSIGNED: We investigated the causal relationship between immune phenotypes and all-cause HF. According to the results, Dendritic cell Absolute Count, CD62l- CD86+ myeloid Dendritic cell Absolute Count, CD62l- CD86+ myeloid Dendritic cell% Dendritic cell, CD39+ CD8+ T cell% CD8+ T cell, CD3 on Central Memory CD4+ T cell aggravate HF, and the risk of HF is decreased by CD14+ CD16+ monocyte% monocyte. These phenotypes may serve as new biomarkers, providing new therapeutic insights for the prevention and treatment of all-cause HF.

UNASSIGNED: Serum 25-hydroxyvitamin D level is associated with erectile dysfunction (ED) in observational studies. However, whether there is a causal association between them remains uncertain.
UNASSIGNED: Conduct a two-sample Mendelian randomization (MR) analysis to investigate the causal effect between serum 25-hydroxyvitamin D level and ED risk.
UNASSIGNED: Genome-wide association study (GWAS) data of serum 25-hydroxyvitamin D levels comprising 6,896,093 single nucleotide polymorphisms (SNP) from 496,949 people of European ancestry were regarded as exposure for the MR analysis. Additional GWAS data involving 9,310,196 SNPs of 6,175 European ED cases and 217,630 controls were used as outcome data. The MR-Egger, inverse variance weighted (IVW) method, weighted median, simple mode, and weighted mode were employed to evaluate causal effects, among which IVW was the primary MR analysis method. The stability of the MR analysis results was confirmed by a heterogeneity test, a horizontal pleiotropy test, and the leave-one-out method.
UNASSIGNED: There were 103 SNPs utilized as instrumental variables (p < 5 × 10-8). The results of MR analysis showed no causal effects of serum 25(OH) D concentration on ED risks (IVW; OR = 0.9516, 95% CI = 0.7994 to 1.1328, p = 0.5772). There was no heterogeneity and pleiotropy in the statistical models.
UNASSIGNED: The present MR study did not support a causal association for genetically predicted serum 25-hydroxyvitamin D concentration in the risk of ED in individuals of European descent.

Oppositional defiant symptoms are some of the most common developmental symptoms in children and adolescents with and without oppositional defiant disorder. Research has addressed the close association of the parent-child relationship (PCR) with oppositional defiant symptoms. However, it is necessary to further investigate the underlying mechanism for forming targeted intervention strategies. By using a machine learning-based causal forest (CF) model, we investigated the heterogeneous causal effects of the PCR on oppositional defiant symptoms in children in Chinese elementary schools. Based on the PCR improvement in two consecutive years, 423 children were divided into improved and control groups. The assessment of oppositional defiant symptoms (AODS) in the second year was set as the dependent variable. Additionally, several factors based on the multilevel family model and the baseline AODS in the first year were included as covariates. Consistent with expectations, the CF model showed a significant causal effect between the PCR and oppositional defiant symptoms in the samples. Moreover, the causality exhibited heterogeneity. The causal effect was greater in those children with higher baseline AODS, a worse family atmosphere, and lower emotion regulation abilities in themselves or their parents. Conversely, the parenting style played a positive role in causality. These findings enhance our understanding of how the PCR contributes to the development of oppositional defiant symptoms conditioned by factors from a multilevel family system. The heterogeneous causality in the observation data, established using the machine learning approach, could be helpful in forming personalized family-oriented intervention strategies for children with oppositional defiant symptoms.