Association between gut microbiota and preeclampsia-eclampsia: a two-sample Mendelian randomization study

Causal effects between gut microbiota and endometriosis: a two-sample Mendelian randomisation study

BACKGROUND

Previous observational evidence has indicated the potential involvement of the gut microbiota (GM) in the development of endometriosis. However, the causal relationship of the association remains to be investigated.

METHOD

Genome-wide association study (GWAS) data of GM was obtained from the MiBioGen consortium, and GWAS for endometriosis data was from the FinnGen consortium. Initially, a two-sample Mendelian randomisation (MR) analysis was performed to identify specific bacteria associated with endometriosis. Inverse variance-weighted (IVW) was used as the main MR analysis to infer causal relationships. The other four popular MR methods including MR-Egger regression, weighted mode, weighted median, and simple mode were used for secondary confirmation. Subsequently, these selected bacteria were employed as exposure to investigate their causal effects on six sub-types of endometriosis. Furthermore, reverse MR analysis was implemented to evaluate the reverse causal effects. Cochran's Q statistics was used to test the heterogeneity of instrumental variables (IVs); MR-Egger regression was used to test horizontal pleiotropy; MR-PRESSO and leave-one-out sensitivity analysis were applied to find significant outliers.

RESULT

A total of 1131 single nucleotide polymorphisms (SNPs) were collected as IVs for 196 GM taxa with endometriosis as the outcome. We identified 12 causal relationships between endometriosis and GM taxa including 1 phylum, 3 families, 2 orders, and 6 genera (Rikenellaceae RC9 gut group, Eubacterium ruminantium group, Faecalibacterium, Peptococcus, Clostridium sensu stricto 1, and Ruminococcaceae UCG005). Utilizing the Bonferroni method, we identified phylum Cyanobacteria as the strongest associated GM taxa. Subsequently, 6 significant causal effects were uncovered between the 12 selected specific GM and 6 sub-types of endometriosis. Meanwhile, no reverse causal relationship was found. Further, no horizontal pleiotropy and no significant outliers were detected in the sensitive analysis.

CONCLUSIONS

This MR analysis revealed significant causal effects between GM and endometriosis and phylum Cyanobacteria had the strongest association.

Association between the gut microbiota and diabetic nephropathy: a two-sample Mendelian randomization study

Numerous studies have revealed a correlation between the risk of developing diabetic nephropathy (DN) and the gut microbiota (GM) composition. However, it remains uncertain whether the GM composition causes DN. We aimed to explore any potential causal links between the GM composition and the risk of developing DN. A meta-analysis conducted by the MiBioGen consortium of the largest genome-wide association study (GWAS) provided aggregated data on the GM. DN data were obtained from the IEU database. The inverse-variance weighting (IVW) method was employed as the primary analytical approach. The IVW analysis indicated that genus Dialister (OR = 0.51, 95% CI: 0.34-0.77, p = 0.00118) was protective against DN. In addition, class Gammaproteobacteria (OR = 0.47, 95% CI: 0.27-0.83, p = 0.0096), class Lentisphaeria (OR =0.76, 95% CI: 0.68-0.99, p = 0.04), order Victivallales (OR = 0.76, 95% CI: 0.58-0.99, p = 0.04), and phylum Proteobacteria (OR = 0.53, 95% CI: 0.33-0.85, p = 0.00872) were negatively associated with the risk of developing DN. Genus LachnospiraceaeUCG008 (OR =1.45, 95% CI: 1.08-1.95, p = 0.01), order Bacteroidales (OR = 1.59, 95% CI: 1.02-2.49, p = 0.04), and genus Terrisporobacter (OR = 1.98, 95% CI: 1.14-3.45, p = 0.015) were positively associated with the risk of developing DN. In this study, we established a causal relationship between the genus Dialister and the risk of developing DN. Further trials are required to confirm the protective effects of probiotics on DN and to elucidate the precise protective mechanisms involving genus Dialister and DN.

Genetic association between gut microbiome and blood pressure and blood cell count as mediator: A two-step Mendelian randomization analysis

BACKGROUND

Previous studies have established a genetic link between gut microbiota and hypertension, but whether blood cell count plays a mediating role in this remains unknown. This study aims to explore genetic associations and causal factors involving the gut microbiome, peripheral blood cell count, and blood pressure.

METHODS

We utilized summary statistics derived from genome-wide association studies to conduct a two-sample mediation Mendelian randomization analysis (https://gwas.mrcieu.ac.uk/). We applied inverse variance weighted (IVW) estimation method as the primary method, along with MR Egger, Weighted median, Simple mode and Weighted mode as complementary methods. To ensure the robustness of the results, several sensitivity analyses were conducted.

RESULTS

Genetic variants significantly associated with the microbiome, blood pressure, or peripheral blood cell counts were selected as instrumental variables. Fourteen microbial taxa were found to have suggestive associations with diastolic blood pressure (DBP), while fifteen microbial taxa showed suggestive associations with systolic blood pressure (SBP). Meanwhile, red blood cell count, lymphocyte count, and platelet count were identified to mediate the influence of the gut microbiome on blood pressure. Specifically, red cell count was identified to mediate the effects of the phylum Cyanobacteria on DBP (mediated proportion: 8.262 %). Lymphocyte count was found mediate the effects of the genus Subdoligranulum (mediated proportion: 2.642 %) and genus Collinsella (mediated proportion: 2.749 %) on SBP. Additionally, platelet count was found to mediate the relationship between the genus Eubacterium ventriosum group and SBP, explaining 3.421 % of the mediated proportion.

CONCLUSIONS

Our findings highlighted that gut microbiota may have causal influence on the blood pressure by modulating blood cell counts, which sheds new light on the pathogenesis and potential clinical interventions through the intricate axis of gut microbiome, blood cell counts, and blood pressure.

Exploring the causal effects of depression and antidepressants on COVID-19

BACKGROUND

While existing studies have suggested an increased risk of COVID-19 in patients with depression, the causal impact of MDD on the severity of COVID-19 remains to be validated. Additionally, the potential impact of antidepressant medication on the risk of COVID-19 is not known.

METHODS

In our study, we applied a Mendelian Randomization (MR) method, leveraging summary data from GWAS, to evaluate the potential causal effects of depression on three COVID-19 outcomes. Furthermore, we investigated the causal effects of antidepressants on COVID-19 outcomes. The COVID-19 datasets contain information on various stages of the disease, including SARS-CoV-2 infection (N = 2,597,856), hospitalized COVID-19 (N = 2,095,324), and critical COVID-19 (N = 1,086,211). Datasets for depression and antidepressants were comprised of 1,349,887 and 106,785 participants, respectively.

RESULTS

Employing the inverse variance-weighted (IVW) method, we show a causal association between depression and three COVID-19 outcomes. Specifically, we found that genetic liability to depression is linked to critical COVID-19 (OR: 1.28, 95 % CI: 1.13-1.46), hospitalized COVID-19 (OR: 1.23, 95 % CI: 1.13-1.34), and SARS-CoV-2 infection (OR: 1.06, 95 % CI: 1.02-1.10). Interestingly, the use of antidepressants was not associated with COVID-19, with the odds ratios for critical COVID-19 (OR: 1.05, 95 % CI: 0.88-1.26), hospitalization (OR: 1.01, 95 % CI: 0.90-1.13), and SARS-CoV-2 infection (OR: 1.03, 95 % CI: 0.99-1.08) indicating no causal impact.

CONCLUSION

Our study indicates that genetic liability to depression may increase the susceptibility to COVID-19 and its severe forms. The lack of causal effect of antidepressant use on COVID-19 implies antidepressant medication may counteract the detrimental effect of depression on COVID-19.

Plasma proteome mediate the impact of PM2.5 on stroke: A 2-step Mendelian randomization study

The objectives of this study were to measure the mediation effect of plasma proteins and to clarify their mediating role in the relationship between stroke risk and particulate matter 2.5 (PM2.5) exposure. The possible mediating role of plasma proteins on the causative link between PM2.5 exposure and stroke incidence were examined using a two-step Mendelian randomization (MR) approach based on two-sample Mendelian randomization (TSMR). The findings revealed a significant positive causal relationship between PM2.5 exposure and stroke, with an inverse variance weighted odds ratio of 1.219 (95 % CI: 1.002 - 1.482, P < 0.05). Additionally, a positive causal association was identified between PM2.5 exposure and several plasma proteins, including FAM134B, SAP, ITGB7, Elafin, and DCLK3. Among these, FAM134B, ITGB7, Elafin, and DCLK3 also demonstrated a positive causal association with stroke, whereas only SAP was found to be negatively causally associated with stroke. Remarkably, four plasma proteins, namely DCLK3, FAM134B, Elafin, and ITGB7, were identified as mediators, accounting for substantial proportions (14.5 %, 13.6 %, 11.1 %, and 9.9 %) of the causal association between PM2.5 and stroke. These results remained robust across various sensitivity analyses. Consequently, the study highlights the significant and independent impact of PM2.5 on stroke risk and identifies specific plasma proteins as potential targets for preventive interventions against PM2.5-induced stroke.

Genetic Connectivity of Gut Microbiota and Oral Ulcers: A Mendelian Randomization Study

OBJECTIVES

The aim of this study was to reveal the relationship, if any, between gut microbiota and oral ulcers.

METHODS

We performed a 2-sample Mendelian randomization (MR) study to estimate the roles of gut microbiota in mouth ulcers. The summary datasets of gut microbiota were from the largest genome-wide association study (GWAS) conducted by MiBioGen, and data of mouth ulcers were obtained from UK Biobank. Random effect inverse variance-weighted, weighted median, MR Egger, simple mode and weighted mode were used to estimate the relationship. Sensitivity analyses were conducted to assess the heterogeneity and pleiotropy of instrumental variables. MR Steiger filtering was also applied to orient the causal direction.

RESULTS

Three gut microbiota taxa were positively associated with mouth ulcers: Holdemania (odds ratio [OR] = 1.005, 95% confidence interval [CI]: 1.001-1.009, P = .019), Oxalobacter (OR = 1.004, 95% CI: 1.000-1.007, P = .032), and Ruminococcaceae UCG011 (OR = 1.006, 95% CI: 1.001-1.011, P = .029), while 4 gut microbiota taxa were negatively associated with mouth ulcers: Actinobacteria (OR = 0.992, 95% CI: 0.985-1.000, P = .042), Lactobacillales (OR = 0.995, 95% CI: 0.990-1.000, P = .034), Oscillospira (OR = 0.990, 95% CI: 0.984-0.997, P = .007) and Phascolarctobacterium (OR = 0.992, 95% CI: 0.986-0.997, P = .003). Sensitivity analyses validated the robustness of the association in between.

CONCLUSIONS

This MR study identified a strong association between the quality of gut microbiota and oral ulcers. The findings are likely to expand the therapeutic targets for mouth ulcers.

Causal relationships between gut microbiota, gut metabolites, and diabetic neuropathy: A mendelian randomization study

BACKGROUND

Previous studies have shown a strong correlation between gut microbiota and diabetes and its associated complications. We aimed to evaluate the causal relationships between the gut microbiota, gut metabolites, and diabetic neuropathy.

METHODS

Summary statistics of 211 gut microbiota and 12 gut-related metabolites (β-hydroxybutyric acid, betaine, trimethylamine-N-oxide, carnitine, choline, glutamate, kynurenine, phenylalanine, propionic acid, serotonin, tryptophan, and tyrosine) were obtained from previous genome-wide association studies (GWAS). A two-sample Mendelian randomization (MR) design was used to estimate the effects of gut microbiota and gut metabolites on the risk of diabetic neuropathy based on FinnGen GWAS.

RESULTS

Higher levels of Acidaminococcaceae (OR = 0.62; 95%CI = 0.46 to 0.84; P = 0.002), Peptococcaceae (OR = 0.70; 95%CI = 0.54 to 0.90; P = 0.006), and Eubacterium coprostanoligenes group (OR = 0.68; 95%CI = 0.50 to 0.93; P = 0.016) are genetically determined to provide protection against diabetic neuropathy. Conversely, the presence of Alistipes (OR = 1.65; 95%CI = 1.18 to 2.31; P = 0.003), ChristensenellaceaeR7 group (OR = 1.52; 95%CI = 1.03 to 2.23; P = 0.033), Eggerthella (OR = 1.28; 95%CI = 1.05 to 1.55; P = 0.014), RuminococcaceaeUCG013 (OR = 1.35; 95%CI = 1.01 to 1.82; P = 0.046), and Firmicutes (OR = 1.42; 95%CI = 1.05 to 1.93; P = 0.023) increases the risk of diabetic neuropathy. Moreover, a correlation has been identified between diabetic neuropathy and two gut metabolites: betaine (OR = 0.95; 95%CI = 0.90 to 1.00; P = 0.033) and tyrosine (OR = 1.03; 95%CI = 1.01 to 1.06; P = 0.019). Sensitivity analysis indicated robust results with no sign of heterogeneity or pleiotropy.

CONCLUSION

The present study elucidated the impact of specific gut microbiota and gut metabolites on the susceptibility to diabetic neuropathy. Interventions targeting the improvement of the gut microbiota diversity and composition hold considerable promise as a potential strategy.

Exploring the Relationship Between Sporadic Creutzfeldt-Jakob Disease and Gut Microbiota Through a Mendelian Randomization Study

Observational studies have shown gut microbiota changes in sporadic Creutzfeldt-Jakob disease patients, but the causal relationship remains unknown. We aimed to determine any causal links between gut microbiota and this prion disease. Using Mendelian randomization analysis, we examined the causal relationship between gut microbiota composition and sporadic Creutzfeldt-Jakob disease. Data on gut microbiota (N = 18,340) and disease cases (5208) were obtained. Various analysis methods were used, including inverse variance weighted, Mendelian randomization-Egger, weighted median, simple mode, and weighted mode. In addition, MR-PRESSO was used to evaluate horizontal pleiotropy and detect outliers. Pleiotropy and heterogeneity were assessed, and reverse analysis was conducted. Negative associations were found between sporadic Creutzfeldt-Jakob disease and family Defluviitaleaceae, family Ruminococcaceae, genus Butyricicoccus, genus Desulfovibrio, and genus Eubacterium nodatum. Genus Lachnospiraceae UCG010 showed a positive correlation. Reverse analysis indicated genetic associations between the disease and decreased levels of family Peptococcaceae, genus Faecalibacterium, and genus Phascolarctobacterium, as well as increased levels of genus Butyrivibrio. No pleiotropy, heterogeneity, outliers, or weak instrument bias were observed. This study revealed bidirectional causal effects between specific gut microbiota components and sporadic Creutzfeldt-Jakob disease. Certain components demonstrated inhibitory effects on disease pathogenesis, while others were positively associated with the disease. Modulating gut microbiota may provide new insights into prion disease therapies. Further research is needed to clarify mechanisms and explore treatments for sporadic Creutzfeldt-Jakob disease.

Assessing the causal relationship between obesity and hypothyroidism using Mendelian randomization

To explore the causal relationship between obesity and hypothyroidism and identify risk factors and the predictive value of subclinical hypothyroidism (SCH) in obese patients using Mendelian randomization, this study employed five Mendelian randomization methods (MR Egger, Weighted Median, Inverse Variance Weighted, Simple Mode, and Weighted Mode) to analyze clinical data from 308 obese patients at the People's Hospital of Xinjiang Uygur Autonomous Region, from January 2015 to June 2023. Patients were divided based on thyroid function tests into normal (n = 173) and SCH groups (n = 56). Comparative analyses, along with univariate and multivariate logistic regression, were conducted to identify risk factors for SCH in obese patients. A significant association between obesity and hypothyroidism was established, especially highlighted by the inverse variance weighted method. SCH patients showed higher ages, thyroid-stimulating hormone levels, and thyroid autoantibody positivity rates, with lower T4 and FT4 levels. Age, FT4, thyroid autoantibodies, TPO-Ab, and Tg-Ab were confirmed as risk factors. The predictive value of FT4 levels for SCH in obesity was significant, with an Area Under the Curve (AUC) of 0.632. The study supports a potential causal link between obesity and hypothyroidism, identifying specific risk factors for SCH in obese patients. FT4 level stands out as an independent predictive factor, suggesting its utility in early diagnosis and preventive strategies for SCH.

[Causal relationship between gut microbiota and pigmented villonodular synovitis: a Mendelian randomization analysis]

OBJECTIVE

To investigate the causal relationship between gut microbiota and pigmented villonodular synovitis using Mendelian randomization analysis.

METHODS

We conducted a two-sample Mendelian randomization analysis to investigate the causal relationship between 211 gut microbiome taxa and pigmented villonodular synovitis based on GWAS summary data, with inverse variance weighted (IVW) analysis as the primary result and the other methods as supplementary analyses. The reliability of the results was tested using Cochran's Q test, MR-Egger regression, MR-PRESSO method and conditional Mendelian randomization analysis (cML-MA).

RESULTS

The increased abundance of Barnesiella (OR=3.12, 95% CI: 1.15-8.41, P=0.025) and Rumatococcaceae UCG010 (OR=4.03, 95% CI: 1.19-13.68, P=0.025) may increase the risk of pigmented villous nodular synovitis, and elevated abundance of Lachnospiraceae (OR=0.33, 95% CI: 0.12-0.91, P=0.032), Alistipes (OR=0.16, 95% CI: 0.05-0.53, P=0.003), Blautia (OR=0.20, 95% CI: 0.06-0.61, P=0.005), and Lachnospiraceae FCS020 group (OR=0.38, 95% CI: 0.15-0.94, P=0.036) and Ruminococcaceae UCG014 (OR=0.36, 95% CI: 0.14-0.94, P=0.037) were all associated with a reduced risk of pigmented villonodular synovitis, which were supported by the results of sensitivity analyses. Reverse Mendelian randomization analysis did not reveal any inverse causal association.

CONCLUSION

Increased abundance of specific intestinal microorganisms is associated with increased or decreased risks of developing hyperpigmented villonodular synovitis, and gut microbiota plays an important role in the pathogenesis of this disease.

Causality of genetically determined blood metabolites on inflammatory bowel disease: a two-sample Mendelian randomization study

Inflammatory bowel disease (IBD) is a chronic and recurrent inflammatory disease of the gastrointestinal tract, including two subtypes: Crohn's disease (CD) and ulcerative colitis (UC). Metabolic disorders are important factors in the development of IBD. However, the evidence for the causal relationship between blood metabolites and IBD remains limited. A two-sample MR analysis was applied to evaluate relationships between 486 blood metabolites and IBD. The inverse variance weighted method was chosen as the primary MR analysis method. False discovery rate correction was used to control for false positives in multiple testing. Following complementary and sensitivity analyses were conducted using methods such as weight median, MR-egger, weighted mode, simple mode, Cochran Q test, and MR-PRESSO. Moreover, we performed replication, meta-analysis, Steiger test, and linkage disequilibrium score regression to enhance the robustness of the results. Additionally, we performed metabolic pathway analysis to identify potential metabolic pathways. As a result, we identified four significant causal associations between four blood metabolites and two IBD subtypes. Specifically, one metabolite was identified as being associated with the development of CD (mannose: odds ratio (OR) = 0.19, 95% confidence interval (CI) 0.08-0.43, P = 8.54 × 10-5). Three metabolites were identified as being associated with the development of UC (arachidonate (20:4n6): OR = 0.18, 95% CI 0.11-0.30, P = 2.09 × 10-11; 1, 5-anhydroglucitol: OR = 2.21, 95% CI 1.47-3.34, P = 1.50 × 10-4; 2-stearoylglycerophosphocholine: OR = 2.66, 95% CI 1.53-4.63, P = 5.30 × 10-4). The findings of our study suggested that the identified metabolites and metabolic pathways can be considered as useful circulating metabolic biomarkers for the screening and prevention of IBD in clinical practice, as well as candidate molecules for future mechanism exploration and drug target selection.

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

Background

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.

Methods

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.

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%).

Conclusion

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 association of circulating immune cells and lymphoma: A Mendelian randomization study

Background

Malignant lymphoma (ML) is a group of malignant tumors originating from the lymphatic hematopoietic system. Previous studies have found a correlation between circulating immune cells and ML. Nonetheless, the precise influence of circulating immune cells on ML remains uncertain.

Methods

Based on publicly available genetic data, we explored causal associations between 731 immune cell signatures and ML risk. A total of four types of immune signatures, median fluorescence intensities, relative cell, absolute cell, and morphological parameters were included. Primary analysis was performed using inverse variance weighting (IVW) to assess the causal relationship between circulating immune cells and the risk of ML. Sensitivity analysis was conducted using Cochran's Q test, the Mendelian randomization Egger regression intercept test, and leave-one-out analysis.

Results

ML had a statistically significant effect on immunophenotypes. Twenty-three immunophenotypes were identified to be significantly associated with Hodgkin lymphoma risk through the IVW approach, and the odds ratio values of CD64 on CD14- CD16+ monocyte [2.31, 95% confidence interval (CI) = 1.41-3.79, P1 = 0.001], IgD+ CD24+ B-cell %lymphocyte (2.06, 95% CI = 1.13-3.79, P1 = 0.018), B-cell %lymphocyte (1.94, 95% CI = 1.08-3.50, P1 = 0.027), CD24+ CD27+ B-cell %lymphocyte (1.68, 95% CI = 1.03-2.74, P1 = 0.039), and CD14+ CD16- monocyte %monocyte (1.60, 95% CI = 1.15-2.24, P1 = 0.006) ranked in the top five. Eleven immunophenotypes were identified to be significantly associated with non-Hodgkin lymphoma risk, CD86 on granulocyte (2.35, 95% CI = 1.18-4.69, P1 = 0.015), CD28-CD8+ T-cell absolute count (1.76, 95% CI = 1.03-2.99, P1 = 0.036), CCR2 on myeloid dendritic cell (CD24+ CD27+ B cell, 95% CI = 1.02-1.66, P1 = 0.034), CD3 on effector memory CD8+ T cell (1.29, 95% CI = 1.02-1.64, P1 = 0.012), and natural killer T %lymphocyte (1.28, 95% CI = 1.01-1.62, P1 = 0.046) were ranked in the top five.

Conclusion

This study presents compelling evidence indicating the correlation between circulating immune cells and lymphoma, thus providing guidance for future clinical research.

The causal relationship of depression, anxiety, and neuroticism with endometriosis: A bidirectional 2-sample Mendelian randomization study

Endometriosis, identified by the abnormal growth of endometrial cells beyond the inner lining of the uterus, often manifests through symptoms like painful menstruation and challenges in conceiving. Observational studies suggest that endometriosis is often comorbid with mental disorders, including anxiety and depression. The nature of these connections, whether they are causal, is still debated and calls for further empirical evidence. We utilized a bidirectional 2-sample Mendelian randomization (MR) approach, harnessing genome-wide association study data to explore the connections among depression, anxiety, neuroticism, and endometriosis. To scrutinize the causative connections between mental health issues and endometriosis, Inverse Variance Weighting (IVW) was employed as the primary analytical tool, complemented by Weighted Median Estimation, Simple mode, Weighted mode, and MR-Egger regression for additional analysis. To examine the potential for reverse causation, reverse MR was applied. To strengthen the reliability of our findings, we carried out sensitivity analyses that included heterogeneity tests, tests for pleiotropy, and leave-one-out analyses. The IVW analysis revealed a significant correlation between the genetic inclination towards depression and a heightened risk of developing endometriosis [Odds Ratio (OR) = 1.151, 95% Confidence Interval (CI) = 1.025-1.293, P = .017]. Similarly, a genetic predisposition to neuroticism was significantly associated with an increased risk of endometriosis (OR = 1.128, 95% CI = 1.038-1.226, P = .004). However, no causative link was found between genetic susceptibility to anxiety and the occurrence of endometriosis. Reverse MR analysis did not support a bidirectional genetic susceptibility between endometriosis and psychiatric disorders. The MR analysis presents genetic data supporting the notion that depression and neuroticism are risk factors for endometriosis. Conversely, it found no evidence of a causal connection between anxiety and the development of endometriosis. Enhancing mental health treatment should be considered a preventive measure against endometriosis.

Association between gut microbiota and adrenal disease: a two-sample Mendelian randomized study

Background

Some observational studies and clinical experiments suggest a close association between gut microbiota and metabolic diseases. However, the causal effects of gut microbiota on adrenal diseases, including Adrenocortical insufficiency, Cushing syndrome, and Hyperaldosteronism, remain unclear.

Methods

This study conducted a two-sample Mendelian randomization analysis using summary statistics data of gut microbiota from a large-scale genome-wide association study conducted by the MiBioGen Consortium. Summary statistics data for the three adrenal diseases were obtained from the FinnGen study. The study employed Inverse variance weighting, MR-Egger, and MR-PRESSO methods to assess the causal relationship between gut microbiota and these three adrenal diseases. Additionally, a reverse Mendelian randomization analysis was performed for bacteria found to have a causal relationship with these three adrenal diseases in the forward Mendelian randomization analysis. Cochran's Q statistic was used to test for heterogeneity of instrumental variables.

Results

The IVW test results demonstrate that class Deltaproteobacteria, Family Desulfovibrionaceae, and Order Desulfovibrionales exhibit protective effects against adrenocortical insufficiency. Conversely, Family Porphyromonadaceae, Genus Lachnoclostridium, and Order MollicutesRF9 are associated with an increased risk of adrenocortical insufficiency. Additionally, Family Acidaminococcaceae confers a certain level of protection against Cushing syndrome. In contrast, Class Methanobacteria, Family Lactobacillaceae, Family Methanobacteriaceae, Genus. Lactobacillus and Order Methanobacteriales are protective against Hyperaldosteronism. Conversely, Genus Parasutterella, Genus Peptococcus, and Genus Veillonella are identified as risk factors for Hyperaldosteronism.

Conclusions

This two-sample Mendelian randomization analysis revealed a causal relationship between microbial taxa such as Deltaproteobacteria and Desulfovibrionaceae and Adrenocortical insufficiency, Cushing syndrome, and Hyperaldosteronism. These findings offer new avenues for comprehending the development of adrenal diseases mediated by gut microbiota.

Unraveling the association between gut microbiota and chemotherapy efficacy: a two-sample Mendelian randomization study

Emerging evidence has underscored the complex link between gut microbiota and chemotherapy efficacy; however, establishing causality remains elusive due to confounding factors. This study, leveraging bidirectional two-sample Mendelian randomization (MR) analyses, explores the casual relationship between gut microbiota and chemotherapy efficacy. Utilizing genome-wide association study (GWAS) data from the MiBioGen consortium for gut microbiota and IEU Open GWAS for chemotherapy efficacy, we employed genetic variants as instrumental variables (IVs). The inverse variance weighted (IVW) method, weighted median estimator (WME), and MR-Egger regression method were applied, with sensitivity analyses ensuring robustness. Furthermore, we conducted reverse MR analyses between chemotherapy efficacy and identified significant gut microbial taxa. The results indicated that genus Butyricicoccus (OR = 3.7908, 95% CI: 1.4464-9.9350, P = 0.01), Dorea (OR = 3.3295, 95% CI: 1.2794-8.6643, P = 0.01), Hungatella (OR = 2.6284, 95% CI: 1.0548-6.5498, P = 0.04), and Turicibacter (OR = 2.5694, 95% CI: 1.0392-6.3526, P = 0.04) were positively associated with chemotherapy efficacy using the IVW method. Conversely, family Porphyromonadaceae (OR = 0.2283, 95% CI: 0.0699-0.7461, P = 0.01) and genus Eggerthella (OR = 0.4953, 95% CI: 0.2443-1.0043, P = 0.05) exhibited negative associations. WME demonstrated consistent results with IVW method only for genus Eggerthella (OR = 0.3343, 95% CI: 0.1298-0.8610, P = 0.02). No significant heterogeneity or horizontal pleiotropy was observed. Reverse MR analyses revealed no significant causal effect of chemotherapy on identified gut microbiota. This study sheds light on the intricate relationship between gut microbiota, with a particular emphasis on the genus Eggerthella, and chemotherapy efficacy, offering valuable insights for refining cancer treatment strategies.IMPORTANCEGlobal advancements in cancer treatment, particularly in chemotherapy, have notably decreased mortality rates in recent years. However, the correlation between gut microbiota and chemotherapy efficacy remains elusive. Our study, emphasizing the role of genus Eggerthella, represented a crucial advance in elucidating this intricate interplay. The identified associations offer potential therapeutic targets, contributing to global efforts for enhanced treatment precision and improved patient outcomes. Furthermore, our findings hold promise for personalized therapeutic interventions, shaping improved strategies in the ever-evolving landscape of cancer treatment.

Anorexia and bulimia in relation to ulcerative colitis: a Mendelian randomization study

Background

Evidence for anorexia and bulimia in relation to the risk of ulcerative colitis (UC) is limited and inconsistent. The objective of this research was to utilize bi-directional, two-sample Mendelian randomization (MR) analysis to predict the causal association between anorexia nervosa and bulimia nervosa with UC.

Methods

The genome-wide association studies (GWAS) provided data for anorexia and bulimia from the UK Biobank, utilizing single-nucleotide polymorphisms (SNP) as instrumental variables. Additionally, genetic associations with UC were collected from various sources including the FinnGen Biobank, the UK Biobank and the International Inflammatory Bowel Disease Genetics Consortium (IIBDGC). The main analytical approach utilized in this study was the inverse-variance-weighted (IVW) method. To evaluate horizontal pleiotropy, the researchers conducted MR-Egger regression and MR-PRESSO global test analyses. Additionally, heterogeneity was assessed using the Cochran's Q test.

Results

This study found a negative association between genetically predicted bulimia (OR = 0.943, 95% CI: 0.893-0.996; p = 0.034) and the risk of UC in the IIBDGC dataset, indicating that individuals with bulimia have approximately a 5.7% lower risk of developing UC. No association was observed in the other two datasets. Conversely, genetically predicted anorexia was not found to be causally associated with UC. In bi-directional Mendelian randomization, UC from the IIBDGC dataset was negatively associated with the risk of anorexia (OR = 0.877, 95% CI: 0.797-0.965; p = 0.007), suggesting that UC patients have approximately a 12.3% lower risk of developing anorexia, but not causally associated with bulimia.

Conclusion

Genetically predicted bulimia may have a negative association with the onset of UC, while genetically predicted anorexia does not show a causal relationship with the development of UC. Conversely, genetically predicted UC may have a negative association with the development of anorexia.

Genetic insights of blood lipid metabolites on polycystic ovary syndrome risk: a bidirectional two-sample Mendelian randomization study

Background

Pathologically, metabolic disorder plays a crucial role in polycystic ovarian syndrome (PCOS). However, there is no conclusive evidence lipid metabolite levels to PCOS risk.

Methods

In this study, genome-wide association study (GWAS) genetic data for 122 lipid metabolites were used to assign instrumental variables (IVs). PCOS GWAS were derived from a large-scale meta-analysis of 10,074 PCOS cases and 103,164 controls. An inverse variance weighted (IVW) analysis was the primary methodology used for Mendelian randomization (MR). For sensitivity analyses, Cochran Q test, MR-Egger intercept, MR-PRESSO, leave-one-out analysis,and Steiger test were performed. Furthermore, we conducted replication analysis, meta-analysis, and metabolic pathway analysis. Lastly, reverse MR analysis was used to determine whether the onset of PCOS affected lipid metabolites.

Results

This study detected the blood lipid metabolites and potential metabolic pathways that have a genetic association with PCOS onset. After IVW, sensitivity analyses, replication and meta-analysis, two pathogenic lipid metabolites of PCOS were finally identified: Hexadecanedioate (OR=1.85,95%CI=1.27-2.70, P=0.001) and Dihomo-linolenate (OR=2.45,95%CI=1.30-4.59, P=0.005). Besides, It was found that PCOS may be mediated by unsaturated fatty acid biosynthesis and primary bile acid biosynthesis metabolic pathways. Reverse MR analysis showed the causal association between PCOS and 2-tetradecenoyl carnitine at the genetic level (OR=1.025, 95% CI=1.003-1.048, P=0.026).

Conclusion

Genetic evidence suggests a causal relationship between hexadecanedioate and dihomo-linolenate and the risk of PCOS. These compounds could potentially serve as metabolic biomarkers for screening PCOS and selecting drug targets. The identification of these metabolic pathways is valuable in guiding the exploration of the pathological mechanisms of PCOS, although further studies are necessary for confirmation.

Genetic causal association between gut microbiota and sepsis: Evidence from a two-sample bidirectional Mendelian randomization analysis

Background

Sepsis is a severe and potentially life-threatening condition characterized by a dysregulated host response and organ dysfunction. The causal relationship between intestinal microbiota and sepsis is unclear.

Methods

A two-sample Mendelian randomization (MR) study was performed to proxy the causal association between gut microbiota and sepsis. The genome-wide association study (GWAS) data of sepsis and gut microbiome were collected from the Integrative Epidemiology Unit (IEU) OpenGWAS, with summary-level data obtained from the UK Biobank. Five traditional methods were used to estimate the potential causal relationships between gut microbiota and sepsis, including the inverse-variance weighted method, weighted median method, MR-Egger regression, simple mode, and weighted mode. Reverse MR analysis was performed on the bacteria that were found to be causally associated with sepsis in forward MR analysis. Cochran's Q statistic was used to quantify the heterogeneity of instrumental variables.

Results

The inverse-variance weighted estimate suggested that class Lentisphaeria (odds ratio [OR]=0.86, 95% confidence interval [CI]: 0.78 to 0.94, P=0.0017, q=0.1596) and order Victivallales (OR=0.86, 95% CI: 0.78 to 0.94, P=0.0017, q=0.1596) have a protective effect on sepsis. The genus Eubacterium eligens group (OR=1.34, 95% CI: 1.11 to 1.63, P=0.0029, q=0.1881) was positively associated with the risk of sepsis. Sepsis may be a significant risk factor for genus Odoribacter (OR=1.18, 95% CI: 1.10 to 1.39, P=0.0415, q=0.9849) and Phascolarctobacterium (OR=1.21, 95% CI: 1.00 to 1.46, P=0.0471, q=0.9849), but this effect was not statistically significant after false discovery rate correction. There was a suggestive association between sepsis and Faecalibacterium (OR=0.85, 95% CI: 0.73 to 0.98, P=0.0278) and Ruminococcus 1 (OR=0.85, 95% CI: 0.73 to 1.00, P=0.0439), which were not significant after false discovery rate correction (q>0.2).

Conclusions

This study found that class Lentisphaeria, order Victivallales, and genus Eubacterium eligens group may have a causal relationship with the risk of sepsis.

A Bidirectional Mendelian Randomization Study of Gut Microbiota and Cerebral Small Vessel Disease

BACKGROUND

The causal nature of gut microbiota and cerebral small vessel disease (CSVD) is still obscure regardless of evidence supporting their observational correlations.

OBJECTIVES

The primary objective of this research is to investigate the potentially pathogenic or protective causal impacts of specific gut microbiota on various neuroimaging subtypes of CSVD.

METHODS

We obtained the latest summary-level genome-wide databases for gut microbiota and 9 CSVD traits. The univariable and multivariable Mendelian randomization (MR) studies were conducted to examine the possible causal link between exposure and outcome. Meanwhile, we conducted sensitivity analyses sequentially, containing the heterogeneity, pleiotropy, and leave-one-out analysis. Additionally, to clarify the potential bidirectional causality, the causality from CSVD traits to the identified gut microbiota was implemented through reverse MR analysis.

RESULTS

The univariable MR analysis identified 22 genetically predicted bacterial abundances that were correlated with CSVD traits. Although conditioning on macronutrient dietary compositions, 2 suggestive relationships were retained using the multivariable MR analysis. Specifically, the class Negativicutes and order Selenomonadales exhibited a negative causal association with strictly lobar cerebral microbleeds, one neuroimaging trait of CSVD. There is insufficient evidence indicating the presence of heterogeneity and horizontal pleiotropy. Furthermore, the identified causal relationship was not driven by any single nucleotide polymorphism. The results of the reverse MR analysis did not reveal any statistically significant causality from CSVD traits to the identified gut microbiota.

CONCLUSIONS

Our study indicated several suggestive causal effects from gut microbiota to different neuroimaging subtypes of CSVD. These findings provided a latent understanding of the pathogenesis of CSVD from the perspective of the gut-brain axis.

Causal relationships between immune cell phenotypes and lung adenocarcinoma: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Lung adenocarcinoma (LUAD) is the most common type of lung cancer and closely associated with the immune system. Emerging evidence suggests that blood immune cell phenotypes in patients with LUAD may undergo alterations. Nevertheless, the limited amount of relevant research makes it difficult to understand the causal links between LUAD and changes in the immune cells. This study aimed to reveal the potential causal relationships between 731 immune cell phenotypes and LUAD.

METHODS

A bidirectional two-sample Mendelian randomization (MR) analysis was used to clarify causal relationships. Four types of immune phenotypes, absolute cell counts, relative cell counts, median fluorescence intensities (MFIs) of surface antigens, and morphological parameters, were investigated in this study. Heterogeneity tests, horizontal pleiotropy tests, and leave-one-out analyses were performed to validate the reliability of our study.

RESULTS

A total of 26 immune cell characteristics were identified as contributing to the occurrence of LUAD. Memory B cells, IgD-CD38br cells, CD4+ regulatory T cells (Tregs), and plasmacytoid dendritic cells (DCs) may play a role in the development of LUAD. Through reverse MR, our study discovered that the presence of LUAD also induced changes in the expression levels of 16 immune cell traits involving specific surface markers and various types of immune cells, some of which pertain to antigen presentation and immune activation processes.

CONCLUSION

Our study demonstrated causal links between several immune cell phenotypes and LUAD, thereby providing indications of the potentially oncogenic physiological state and early screening biomarkers for future research.

Associations between type 1 diabetes and autoimmune skin diseases: Mendelian randomization analysis

Background

Type 1 diabetes mellitus (T1DM) may be associated with various autoimmune diseases, but the causal relationship between T1DM and autoimmune skin diseases is not yet clear.

Methods

The summary statistical data on T1DM and nine autoimmune skin diseases in European populations were extracted for mendelian randomization (MR) analysis. Subsequently, the analysis was replicated in East Asian populations. In the MR estimation, inverse variance-weighted (IVW), MR-Egger, weighted median, simple mode, and weighted mode methods were utilized. Outliers were excluded using MR-PRESSO, and horizontal pleiotropy was assessed with MR-Egger. Additionally, a multivariable MR analysis was conducted to investigate whether T1DM has an independent effect on autoimmune skin diseases after adjusting for potential confounders.

Results

In Europe, the MR estimated based on IVW method indicated a causal association between genetically determined T1DM and systemic lupus erythematosus (SLE) (OR = 1.38, 95%CI: 1.26-1.50, p＜0.01), rheumatoid arthritis (RA) (OR = 1.15, 95%CI: 1.05-1.25, p＜0.01), as well as multiple sclerosis (MS) (OR = 1.17, 95%CI: 1.01-1.36, p = 0.04), but there is no association between T1DM and atopic dermatitis (AD), vitiligo, lichen planus (LP), hidradenitis suppurativa (HS), alopecia areata (AA) and systemic sclerosis (SS). After adjusting for time spent watching television, body mass index, type 2 diabetes mellitus, and body fat percentage, we found a causal relationship between T1DM and SLE (OR = 1.29, 95%CI: 1.16-1.44, p < 0.01), RA (OR = 1.28, 95%CI: 1.20-1.38 p < 0.01) and MS (OR = 1.11, 95%CI: 1.04-1.18, p < 0.01). Then, no genetic causal association was found between TIDM and SLE, and AD in East Asia. These results didn't exhibit horizontal pleiotropy, and "leave-one-out" analysis demonstrated result stability.

Conclusion

Our MR research indicates a causal relationship between T1DM and SLE, RA, and MS in Europe. However, no causal relationship between T1DM and SLE has been observed in East Asia. Therefore, it is important to regularly monitor relevant immunological markers of SLE, RA, and MS in T1DM patients and take preventive measures.

Mendelian randomization as a cornerstone of causal inference for gut microbiota and related diseases from the perspective of bibliometrics

Gut microbiota, a special group of microbiotas in the human body, contributes to health in a way that can't be ignored. In recent years, Mendelian randomization, which is a widely used and successful method of analyzing causality, has been investigated for the relationship between the gut microbiota and related diseases. Unfortunately, there seems to be a shortage of systematic bibliometric analysis in this field. Therefore, this study aims to investigate the research progress of Mendelian randomization for gut microbiota through comprehensive bibliometric analysis. In this study, publications about Mendelian randomization for gut microbiota were gathered from 2013 to 2023, utilizing the Web of Science Core Collection as our literature source database. The search strategies were as follows: TS = (intestinal flora OR gut flora OR intestinal microflora OR gut microflora OR intestinal microbiota OR gut microbiota OR bowel microbiota OR bowel flora OR gut bacteria OR intestinal tract bacteria OR bowel bacteria OR gut metabolites OR gut microbiota) and TS = (Mendelian randomization). VOSviewer (version 1.6.18), CiteSpace (version 6.1.R1), Microsoft Excel 2021, and Scimago Graphica were employed for bibliometric and visualization analysis. According to research, from January 2013 to August 2023, 154 publications on Mendelian randomization for gut microbiota were written by 1053 authors hailing from 332 institutions across 31 countries and published in 86 journals. China had the highest number of publications, with 109. Frontiers in Microbiology is the most prolific journal, and Lei Zhang has published the highest number of significant articles. The most popular keywords were "Mendelian randomization," "gut microbiota," "instruments," "association," "causality," "gut microbiome," "risk," "bias," "genome-wide association," and "causal relationship." Moreover, the current research hotspots in this field focus on utilizing a 2-sample Mendelian randomization to investigate the relationship between gut microbiota and associated disorders. This research systematically reveals a comprehensive overview of the literature that has been published over the last 10 years about Mendelian randomization for gut microbiota. Moreover, the knowledge of key information in the field from a bibliometric perspective may greatly facilitate future research in the field.

Endometriosis is a disease of immune dysfunction, which could be linked to microbiota

Background: Endometriosis, characterized by extrauterine endometrial tissue, leads to irregular bleeding and pelvic pain. Menstrual retrograde theory suggests fragments traverse fallopian tubes, causing inflammation and scar tissue. Prevalent among infertile women, risk factors include fewer pregnancies, delayed childbirth, irregular cycles, and familial predisposition. Treatments, medication, and surgery entail side effects. Studies link gut microbiota alterations to endometriosis, necessitating research to establish causation. We used Mendelian randomization to investigate the potential link between endometriosis and gut microbiota through genetic variants. Methods: Two-sample Mendelian randomization analyzed gut microbiota's potential causal effects on endometriosis. Instrumental variables, robustly associated with exposures, leveraged GWAS data from MiBioGen for gut microbiota and FinnGen R8 release for endometriosis. SNPs strongly associated with exposures were instrumental variables. Rigorous assessments ensured SNP impact scrutiny on endometriosis. Results: At the genus level, Anaerotruncus, Desulfovibrio, Haemophilus, and Holdemania showed causal association with endometriosis. Specific gut microbiota exhibited causal effects on different endometriosis stages. Holdemania and Ruminococcaceae UCG002 exerted reversible, stage-specific impacts. Conclusion: Mendelian randomization provides evidence for the causal link between specific gut microbiotas and endometriosis, emphasizing the pivotal role of gut microbiota dysbiosis. Modulating gut microbiota emerges as a promising strategy for preventing and treating endometriosis.

No Evidence of an Association between Genetic Factors Affecting Response to Vitamin A Supplementation and Myopia: A Mendelian Randomization Study and Meta-Analysis

The relationship between vitamin A supplementation and myopia has been a topic of debate, with conflicting and inconclusive findings. We aimed to determine whether there is a causal relationship between vitamin A supplementation and the risk of myopia using Mendelian randomization (MR) and meta-analytical methods. Genetic variants from the UK Biobank and FinnGen studies associated with the response to vitamin A supplementation were employed as instrumental variables to evaluate the causal relationship between vitamin A supplementation and myopia. Fixed-effects meta-analysis was then used to combine MR estimates from multiple sources for each outcome. The meta-analysis of MR results found no convincing evidence to support a direct causal relationship between vitamin A supplementation and myopia risk (odds ratio (OR) = 0.99, 95% confidence interval (CI) = 0.82-1.20, I2 = 0%, p = 0.40). The analysis of three out of the four sets of MR analyses indicated no direction of causal effect, whereas the other set of results suggested that higher vitamin A supplementation was associated with a lower risk of myopia (OR = 0.002, 95% CI 1.17 × 10-6-3.099, p = 0.096). This comprehensive MR study and meta-analysis did not find valid evidence of a direct association between vitamin A supplementation and myopia. Vitamin A supplementation may not have an independent effect on myopia, but intraocular processes associated with vitamin A may indirectly contribute to its development.

Causal associations of gut microbiota and pulmonary tuberculosis: a two-sample Mendelian randomization study

Background

The prevalence of pulmonary tuberculosis (PTB) as an infectious disease continues to contribute significantly to global mortality. According to recent studies, the gut microbiota of PTB patients and healthy controls (HCs) show significant disparities. However, the causal relationship between them has yet to be elucidated.

Methods

We conducted a study using Mendelian Randomization (MR) to explore the potential causal link between gut microbiota and pulmonary tuberculosis (PTB). The summary statistics of the gut microbiota were acquired from the MiBioGen consortium, while data on PTB were sourced from pheweb.jp. A range of statistical methodologies were employed to evaluate causality, encompassing inverse variance weighting (IVW), MR-Egger, weighted median (WM), weighted model, and simple model. We utilized instrumental variables (IVs) that have a direct causal relationship with PTB to annotate SNPs, aiming to discover the genes harboring these genetic variants and uncover potential associations between host genes and the microbiome in patients with PTB.

Results

Among the 196 bacterial traits in the gut microbiome, we have identified a total of three microbiomes that exhibit a significant association with PTB. The occurrence of Dorea (P = 0.0458, FDR-adjusted P = 0.0458) and Parasutterella (P = 0.0056, FDR-adjusted P = 0.0168) was linked to an elevated risk of PTB, while the presence of Lachnoclostridium (P = 0.0347, FDR-adjusted P = 0.0520) demonstrated a protective effect against PTB. Our reverse Two-Sample Mendelian Randomization (TSMR) analysis did not yield any evidence supporting the hypothesis of reverse causality from PTB to alterations in the intestinal flora.

Conclusion

We have established a connection between the gut microbiota and PTB through gene prediction analysis, supporting the use of gut microecological therapy in managing PTB and paving the way for further understanding of how gut microbiota contributes to PTB's development.

Causal Relationships Between Circulating Inflammatory Proteins and Obstructive Sleep Apnea: A Bidirectional Mendelian Randomization Study

Purpose

Clinical studies have demonstrated the intricate association between the onset and progression of obstructive sleep apnea (OSA) and the activation of the inflammatory cascade reaction. This study delves into investigating the causal links between 91 circulating inflammatory proteins (CIPs) and OSA through the application of Mendelian randomization (MR) techniques.

Methods

Utilizing genetic data on OSA sourced from the Finnish Biobank (FinnGen) Genome-wide Association Studies (GWAS) of the European population, alongside summary-level GWAS data of CIPs from 14,824 European participants, we conducted a bidirectional MR study.

Results

This study suggests that several factors may be associated with the risk of OSA. IL-17C (odds ratio (OR) = 1.090, p = 0.0311), CCL25 (OR = 1.079, p = 0.0493), FGF-5 (OR = 1.090, p = 0.0003), CD5 (OR = 1.055, p = 0.0477), and TNFSF14 (OR = 1.092, p = 0.0008) may positively correlate with OSA risk. Conversely, IL-20RA (OR = 0.877, p = 0.0107), CCL19 (OR = 0.933, p = 0.0237), MIP-1 alpha (OR = 0.906, p = 0.0042), Flt3L (OR = 0.941, p = 0.0019), CST5 (OR = 0.957, p = 0.0320), OPG (OR = 0.850, p = 0.0001), and TRAIL (OR = 0.956, p = 0.0063) may reduce the risk of OSA. Additionally, elevated levels of IL-10RA (OR = 1.153, p = 0.0478) were observed as a consequence of OSA. Conversely, OSA may potentially lead to decreased levels of CCL28 (OR = 0.875, p = 0.0317), DNER (OR = 0.874, p = 0.0324), FGF-21 (OR = 0.846, p = 0.0344), and CSF-1 (OR = 0.842, p = 0.0396).

Conclusion

Through this bidirectional MR study, we have identified 12 upstream regulatory proteins and 5 downstream effect proteins that are linked to OSA. These findings hold promise in providing potential therapeutic targets for the inflammatory mechanisms underlying OSA.

The causal effect of exposure to air pollution on risk of adverse pregnancy outcomes: A two-sample Mendelian randomisation study

BACKGROUND

Epidemiological studies have examined the relation between air pollution (NOx, NO2, PM2.5, PM2.5-10, and PM10) and adverse pregnancy outcomes (APOs). There's increasing evidence that air pollution increases the risk of APOs. However, the results of these studies are controversial, and the causal relation remains uncertain. We aimed to assess whether a genetic causal link exists between air pollution and APOs and the potential effects of this relation.

METHODS

A novel two-sample Mendelian randomisation (MR) study used pooled data from a large-scale complete genome correlation study. The primary analysis method was inverse variance weighting (IVW), which explored the expose-outcome relationship for assessing single nucleotide polymorphisms (SNPs) associated with air pollution. Further sensitivity analysis, including MR-PRESSO, MR-Egger regression, and leave-one analysis, was used to test the consistency of the results.

RESULTS

There was a significant correlation between air pollution-related SNPs and APOs. A robust causal link was found between genetic susceptibility to air pollution and APOs.

CONCLUSIONS

Our MR analysis reveals a genetic causal relation between air pollution and APOs, which may help provide new insights into further mechanisms and clinical studies in air pollution-mediated APOs.

Genetic association of the gut microbiota with epigenetic clocks mediated by inflammatory cytokines: a Mendelian randomization analysis

Background

A new aging biomarker epigenetic clock has been developed. There exists a close link between aging and gut microbiota, which may be mediated by inflammatory cytokines. However, the relationship between the epigenetic clock, gut microbiota, and the mediating substances is unclear.

Methods

Two large genome-wide association meta-analyses were analyzed by two-sample Mendelian randomization. The results between gut microbiota and epigenetic clock were investigated using the four methods (Inverse variance weighted, MR-Egger, weighted median, MR-PRESSO). Genetic correlation was measured by Linked disequilibrium score regression (LDSC). The correctness of the study direction was checked by the Steiger test. Cochran's Q statistic and MR-Egger intercept were used as sensitivity analyses of the study. The two-step method was used to examine the mediating role of inflammatory cytokines. We use the Benjamini-Hochberg correction method to correct the P value.

Results

After FDR correction, multiple bacterial genera were significantly or suggestively associated with four epigenetic clocks (GrimAge, HannumAge, IEAA, PhenoAge). And we detected several inflammatory factors acting as mediators of gut microbiota and epigenetic clocks.

Conclusion

This study provides genetic evidence for a positive and negative link between gut microbiota and aging risk. We hope that by elucidating the genetic relationship and potential mechanisms between aging and gut microbiota, we will provide new avenues for continuing aging-related research and treatment.

Causal relationship between immune cells and aortic aneurysms: a Mendelian randomization study

OBJECTIVES

The causal association between immune cell traits and aortic aneurysm remains unknown.

METHODS

We performed a bidirectional two-sample Mendelian randomization analysis to explore the causality between 731 immune cell characteristics and the risk of abdominal aortic aneurysm and thoracic aortic aneurysms through publicly available genetic data, respectively. To examine heterogeneity and horizontal pleiotropy, Cochran's Q test and MR-Egger intercept were utilized. Additionally, multivariable Mendelian randomization analysis and meta-analysis were performed in further analysis.

RESULTS

We found that 20 immune phenotypes had a suggestive causality on abdominal aortic aneurysm, and 15 immune phenotypes had a suggestive causal effect on thoracic aortic aneurysm. After further false discovery rate adjustment (q value <0.1), CD20 on IgD+ CD38- B cell (q = 0.053) and CD127 on CD28+ CD4+ T cell (q = 0.096) were associated with an increased risk of abdominal aortic aneurysm, respectively, indicating a significant causality between them. After adjusting for smoking, there is still statistical significance between CD127 on CD28+ CD4+ T cell and abdominal aortic aneurysm. However, after adjusting for lipids, no statistical significance can be observed between CD127 on CD28+ CD4+ T cells and abdominal aortic aneurysm. Furthermore, there is still statistical significance between CD20 on IgD+ CD38- B cells and abdominal aortic aneurysm after adjusting for lipids and smoking, which was further identified by meta-analysis.

CONCLUSIONS

We found a causal association between immune cell traits and aortic aneurysm by genetic methods, thus providing new avenues for future mechanism studies.

Gut microbiota and postpartum depression: a Mendelian randomization study

Background

Increasing evidence suggests a correlation between intestinal microbiota and the gut-brain axis; however, the causal relationship between gut microbiota and postpartum depression (PPD) remains unclear.

Methods

In this study, a two-sample Mendelian randomization (MR) design was employed to analyze the GWAS data of gut microorganisms from the Mibiogen database and PPD data from the UK biobank. Various statistical methods, including inverse variance weighted, MR-Egger, weighted median, weighted model, and MR-PRESSO, were utilized to investigate the causal relationship between gut microbiota and PPD. Additionally, sensitivity analysis was conducted to assess the robustness of the findings.

Results

Through MR analysis, it was found that phylum Actinobacteria (P=0.014, OR=0.971, 95% CI=0.948-0.994) and genus Holdemanella (P=0.023, OR=0.979, 95% CI=0.961-0.997) have protective effects on PPD, while the other two unknown genera, genus Unknown Ids 2001 (P=0.025, OR=0.972,95% CI=0.947-0.996), and genus Unknown Ids 2755 (P=0.012, OR=0.977, 95% CI=0.959-0.995) also has a protective effect on PPD. The sensitivity analysis results indicate that there is no heterogeneity or horizontal pleiotropy.

Conclusion

This study has identified a causal association between Actinomycetota, Holdemanella, and PDD through MR analysis. These findings offer significant contributions to the development of personalized treatment approaches for PPD, encompassing interventions such as dietary modifications or microbiome interventions.

From Oral Health to Obstetric Outcomes: A Comprehensive Review of Periodontal Disease and Its Implications for Preeclampsia

Periodontal disease and preeclampsia (PE) are both significant health concerns with implications for maternal and fetal well-being. Emerging evidence suggests a potential association between these two conditions, prompting increased interest in understanding their relationship and clinical implications. This comprehensive review examines the current literature on periodontal disease and PE, focusing on epidemiological evidence, proposed mechanistic pathways, and clinical implications. Epidemiological studies consistently demonstrate an increased risk of PE among pregnant individuals with periodontal disease, independent of traditional risk factors. Proposed mechanisms linking periodontal disease to PE include systemic inflammation, endothelial dysfunction, and immune dysregulation. The implications for research include the need for well-designed prospective studies and randomized controlled trials to elucidate further the mechanisms underlying the association and evaluate the effectiveness of periodontal interventions in preventing PE. Clinicians should be aware of the potential link between periodontal disease and PE and consider screening pregnant individuals for periodontal disease as part of routine prenatal care. Interdisciplinary collaboration between obstetricians and periodontists may be beneficial in managing pregnant individuals with periodontal disease to mitigate the risk of PE. By addressing these research gaps, we can further understand the relationship between oral health and obstetric outcomes and develop evidence-based strategies to improve maternal and fetal health.

Complex causal association between genetically predicted 731 immunocyte phenotype and osteonecrosis: a bidirectional two-sample Mendelian randomization analysis

PURPOSE

Previous studies have explored the role of immune cells on osteonecrosis. This Mendelian randomization (MR) study further assessed 731 immunocyte phenotypes on osteonecrosis, whether a causal relationship exists, and provides some evidence of causality.

METHODS

The 731 immunocyte phenotypes and osteonecrosis data used in this study were obtained from their respective genome-wide association studies (GWAS). The authors used inverse variable weighting (IVW) as the primary analysis method. In addition, the authors simultaneously employed multiple analytical methods, including MR-Egger, weighted mode, simple mode, and weighted median, to strengthen the final results. Finally, sensitivity analyses were conducted to verify the stability and feasibility of the data.

RESULTS

The results of the IVW method of MR analysis showed that 8 immunocyte phenotypes were positively associated with osteonecrosis [ P <0.05, odds ratio (OR) > 1]; 18 immunocyte phenotypes were negatively associated with osteonecrosis ( P <0.05, OR<1), none of which were heterogeneous or horizontally pleiotropic ( P > 0.05) or reverse causality. In addition to this, in reverse MR, osteonecrosis was positively associated with 10 additional immunocyte phenotypes ( P <0.05, OR > 1) and negatively associated with 14 immunocyte phenotypes ( P <0.05, OR<1). And none of them had heterogeneity and horizontal pleiotropy ( P > 0.05) or reverse causality.

CONCLUSIONS

The authors demonstrated a complex causal relationship between multiple immune phenotypes and osteonecrosis through a comprehensive two-way, two-sample MR analysis, highlighting the complex pattern of interactions between the immune system and osteonecrosis.

Dried fruit intake can lower the risk of ulcerative colitis: evidence from a Mendelian randomization study

BACKGROUND AND OBJECTIVES

This study aims to examine the causal relationship between dietary factors and ulcerative colitis (UC).

METHODS AND STUDY DESIGN

The analysis utilized data from genome-wide association studies (GWAS). Dried fruit, vegetables, processed meat, fresh fruit, and cereal intake were examined as exposure factors. UC was considered the outcome. Two-sample Mendelian randomization (TSMR) analysis was performed using methods. Heterogeneity and horizontal pleiotropy assessments were conducted to ensure the robustness of our findings. Additionally, we applied False Discovery Rate (FDR) corrections for multiple tests.

RESULTS

The analysis revealed a significant inverse causal relationship between dried fruit intake and UC risk (odds ratio [OR]: 0.488, 95% confidence interval [CI]: 0.261 to 0.915, p = 0.025). No significant association was observed between vegetable intake (OR: 1.742, 95% CI: 0.561 to 5.415, p = 0.337), processed meat intake (OR: 1.136, 95% CI: 0.552 to 2.339, p = 0.729), fresh fruit intake (OR: 0.977, 95% CI: 0.465 to 2.054, p = 0.952), cereal intake (OR: 1.195, 95% CI: 0.669 to 2.134, p = 0.547). The low heterogeneity observed across analyses and the confirmation of stability through leave-one-out analysis reinforce the reliability of these results. Moreover, after adjusting for multiple tests, none of the dietary factors reached a p-value below the conventional significance threshold of 0.05.

CONCLUSIONS

This study provides evidence of a potential association between dried fruit intake and a reduced risk of UC. Further MR studies incorporating larger GWAS datasets are needed to confirm these findings.

Causal effects of gut microbiota on multiple sclerosis: A two-sample Mendelian randomization study

BACKGROUND

Gut microbiota alterations in multiple sclerosis (MS) patients have been reported in observational studies, but whether these associations are causal is unclear.

OBJECTIVE

We performed a Mendelian randomization study (MR) to assess the causal effects of gut microbiota on MS.

METHODS

Independent genetic variants associated with 211 gut microbiota phenotypes were selected as instrumental variables from the largest genome-wide association studies (GWAS) previously published by the MiBioGen study. GWAS data for MS were obtained from the International Multiple Sclerosis Genetics Consortium (IMSGC) for primary analysis and the FinnGen consortium for replication and collaborative analysis. Sensitivity analyses were conducted to evaluate heterogeneity and pleiotropy.

RESULTS

After inverse-variance-weighted and sensitivity analysis filtering, seven gut microbiota with potential causal effects on MS were identified from the IMSGC. Only five metabolites remained significant associations with MS when combined with the FinnGen consortium, including genus Anaerofilum id.2053 (odds ratio [OR] = 1.141, 95% confidence interval [CI]: 1.021-1.276, p = .021), Ruminococcus2 id.11374 (OR = 1.190, 95% CI: 1.007-1.406, p = .042), Ruminococcaceae UCG003 id.11361 (OR = 0.822, 95% CI: 0.688-0.982, p = .031), Ruminiclostridium5 id.11355 (OR = 0.724, 95% CI: 0.585-0.895, p = .003), Anaerotruncus id.2054 (OR = 0.772, 95% CI: 0.634-0.940, p = .010).

CONCLUSION

Our MR analysis reveals a potential causal relationship between gut microbiota and MS, offering promising avenues for advancing mechanistic understanding and clinical investigation of microbiota-mediated MS.

Gut microbiota influence acute pancreatitis through inflammatory proteins: a Mendelian randomization analysis

Background/Aim

We employed Mendelian randomization (MR) analysis to investigate the causal relationship between the gut microbiota, acute pancreatitis, and potential inflammatory proteins.

Methods

The data for gut microbiota, acute pancreatitis, and inflammatory proteins are sourced from public databases. We conducted a bidirectional MR analysis to explore the causal relationship between gut microbiota and acute pancreatitis, and employed a two-step MR analysis to identify potential mediating inflammatory proteins. IVW is the primary analysis method, heterogeneity, pleiotropy, and sensitivity analyses were also conducted simultaneously.

Results

We identified five bacterial genera associated with the risk of acute pancreatitis, namely genus.Coprococcus3, genus.Eubacterium fissicatena group, genus.Erysipelotrichaceae UCG-003, genus.Fusicatenibacter, and genus.Ruminiclostridium6. Additionally, we have discovered three inflammatory proteins that are also associated with the occurrence of acute pancreatitis, namely interleukin-15 receptor subunit alpha (IL-15RA), monocyte chemoattractant protein-4 (CCL13), and tumor necrosis factor receptor superfamily member 9 (TNFRSF9). Following a two-step MR analysis, we ultimately identified IL-15RA as a potential intermediate factor, with a mediated effect of 0.018 (95% CI: 0.005 - 0.032).

Conclusion

Our results support the idea that genus.Coprococcus3 promotes the occurrence of acute pancreatitis through IL-15RA. Furthermore, there is a potential causal relationship between the gut microbiota, inflammatory proteins, and acute pancreatitis. These findings provide new insights for subsequent acute pancreatitis prevention.

Cathepsins and cancer risk: a Mendelian randomization study

Background

Previous observational epidemiological studies reported an association between cathepsins and cancer, however, a causal relationship is uncertain. This study evaluated the causal relationship between cathepsins and cancer using Mendelian randomization (MR) analysis.

Methods

We used publicly available genome-wide association study (GWAS) data for bidirectional MR analysis. Inverse variance weighting (IVW) was used as the primary MR method of MR analysis.

Results

After correction for the False Discovery Rate (FDR), two cathepsins were found to be significantly associated with cancer risk: cathepsin H (CTSH) levels increased the risk of lung cancer (OR = 1.070, 95% CI = 1.027-1.114, P = 0.001, PFDR = 0.009), and CTSH levels decreased the risk of basal cell carcinoma (OR = 0.947, 95% CI = 0.919-0.975, P = 0.0002, P FDR = 0.002). In addition, there was no statistically significant effect of the 20 cancers on the nine cathepsins. Some unadjusted low P-value phenotypes are worth mentioning, including a positive correlation between cathepsin O (CTSO) and breast cancer (OR = 1.012, 95% CI = 1.001-1.025, P = 0.041), cathepsin S (CTSS) and pharyngeal cancer (OR = 1.017, 95% CI = 1.001-1.034, P = 0.043), and CTSS and endometrial cancer (OR = 1.055, 95% CI = 1.012-1.101, P = 0.012); and there was a negative correlation between cathepsin Z and ovarian cancer (CTSZ) (OR = 0.970, 95% CI = 0.949-0.991, P = 0.006), CTSS and prostate cancer (OR = 0.947, 95% CI = 0.902-0.944, P = 0.028), and cathepsin E (CTSE) and pancreatic cancer (OR = 0.963, 95% CI = 0.938-0.990, P = 0.006).

Conclusion

Our MR analyses showed a causal relationship between cathepsins and cancers and may help provide new insights for further mechanistic and clinical studies of cathepsin-mediated cancer.

Causal effect between gut microbiota and metabolic syndrome in European population: a bidirectional mendelian randomization study

BACKGROUND

Observational studies have reported that gut microbiota composition is associated with metabolic syndrome. However, the causal effect of gut microbiota on metabolic syndrome has yet to be confirmed.

METHODS

We performed a bidirectional Mendelian randomization study to investigate the causal effect between gut microbiota and metabolic syndrome in European population. Summary statistics of gut microbiota were from the largest available genome-wide association study meta-analysis (n = 13,266) conducted by the MiBioGen consortium. The summary statistics of outcome were obtained from the most comprehensive genome-wide association studies of metabolic syndrome (n = 291,107). The inverse-variance weighted method was applied as the primary method, and the robustness of the results was assessed by a series of sensitivity analyses.

RESULTS

In the primary causal estimates, Actinobacteria (OR = 0.935, 95% CI = 0.878-0.996, P = 0.037), Bifidobacteriales (OR = 0.928, 95% CI = 0.868-0.992, P = 0.028), Bifidobacteriaceae (OR = 0.928, 95% CI = 0.868-0.992, P = 0.028), Desulfovibrio (OR = 0.920, 95% CI = 0.869-0.975, P = 0.005), and RuminococcaceaeUCG010 (OR = 0.882, 95% CI = 0.803-0.969, P = 0.009) may be associated with a lower risk of metabolic syndrome, while Lachnospiraceae (OR = 1.130, 95% CI = 1.016-1.257, P = 0.025), Veillonellaceae (OR = 1.055, 95% CI = 1.004-1.108, P = 0.034) and Olsenella (OR = 1.046, 95% CI = 1.009-1.085, P = 0.015) may be linked to a higher risk for metabolic syndrome. Reverse MR analysis demonstrated that abundance of RuminococcaceaeUCG010 (OR = 0.938, 95% CI = 0.886-0.994, P = 0.030) may be downregulated by metabolic syndrome. Sensitivity analyses indicated no heterogeneity or horizontal pleiotropy.

CONCLUSIONS

Our Mendelian randomization study provided causal relationship between specific gut microbiota and metabolic syndrome, which might provide new insights into the potential pathogenic mechanisms of gut microbiota in metabolic syndrome and the assignment of effective therapeutic strategies.

Causal relationship between gut microbiota and childhood obesity: A Mendelian randomization study and case-control study

BACKGROUND

Gut microbiota and obesity are deeply interconnected. However, the causality in the relationship between these factors remains unclear. Therefore, this study aimed to elucidate the genetic relationship between gut microbiota and childhood obesity.

METHODS

Genetic summary statistics for the gut microbiota were obtained from the MiBioGen consortium. Genome-wide association studies (GWAS) summary data for childhood obesity were obtained from North American, Australian, and European collaborative genome-wide meta-analyses. Mendelian randomization (MR) analyses were performed using the inverse variance weighting method. 16 children with obesity and 16 without obesity were included for clinical observation, and their weight, body mass index, blood lipid levels, and gut microbiology were assessed. Paired t-test was the primary method of data analysis, and statistical significance was set at P < 0.05.

RESULTS

MR identified 16 causal relationships between the gut microbiome and childhood obesity. In the case-control study, we found that five gut microorganisms differed between children with and without obesity, whereas three gut microorganisms changed after weight loss in children with obesity.

CONCLUSION

Our study provides new insights into the genetic mechanisms underlying gut microbiota and childhood obesity.

TRIAL REGISTRATION NUMBER

ChiCTR2300072179.

NAME OF REGISTRY

Change of intestinal flora and plasma metabolome in obese children and their weight loss intervention: a randomized controlled tria URL OF REGISTRY: https://www.chictr.org.cn/showproj.html.

DATE OF REGISTRATION

2023-06-06.

DATE OF ENROLMENT OF THE FIRST PARTICIPANT TO THE TRIAL

2023-06-07.

Potential drug targets for tumors identified through Mendelian randomization analysis

According to the latest cancer research data, there are a significant number of new cancer cases and a substantial mortality rate each year. Although a substantial number of clinical patients are treated with existing cancer drugs each year, the efficacy is unsatisfactory. The incidence is still high and the effectiveness of most cancer drugs remains unsatisfactory. Therefore, we evaluated the human proteins for their causal relationship to for cancer risk and therefore also their potential as drug targets. We used summary tumors data from the FinnGen and cis protein quantitative trait loci (cis-pQTL) data from a genome-wide association study, and employed Mendelian randomization (MR) to explore the association between potential drug targets and nine tumors, including breast, colorectal, lung, liver, bladder, prostate, kidney, head and neck, pancreatic caners. Furthermore, we conducted MR analysis on external cohort. Moreover, Bidirectional MR, Steiger filtering, and colocalization were employed to validate the main results. The DrugBank database was used to discover potential drugs of tumors. Under the threshold of False discovery rate (FDR) < 0.05, results showed that S100A16 was protective protein and S100A14 was risk protein for human epidermal growth factor receptor 2-positive (HER-positive) breast cancer, phosphodiesterase 5A (PDE5A) was risk protein for colorectal cancer, and melanoma inhibitory activity (MIA) was protective protein for non-small cell lung carcinoma (NSCLC). And there was no reverse causal association between them. Colocalization analysis showed that S100A14 (PP.H4.abf = 0.920) and S100A16 (PP.H4.abf = 0.932) shared causal variation with HER-positive breast cancer, and PDE5A (PP.H4.abf = 0.857) shared causal variation with colorectal cancer (CRC). The MR results of all pQTL of PDE5A and MIA were consistent with main results. In addition, the MR results of MIA and external outcome cohort were consistent with main results. In this study, genetic predictions indicate that circulating S100 calcium binding protein A14 (S100A14) and S100 calcium binding protein A16 (S100A16) are associated with increase and decrease in the risk of HER-positive breast cancer, respectively. Circulating PDE5A is associated with increased risk of CRC, while circulating MIA is associated with decreased risk of NSCLC. These findings suggest that four proteins may serve as biomarkers for cancer prevention and as potential drug targets that could be expected for approval.

Causal relationship between immune cells and atrial fibrillation: A Mendelian randomization study

Atrial fibrillation (AF) is a prevalent cardiac arrhythmia, with recent research indicating a correlation between immune system characteristics and the development of AF. However, it remains uncertain whether the immunological response is the primary underlying component or a secondary consequence of AF. Initially, we investigated the effect of immune cells on AF by performing forward Mendelian randomization (MR) analyses with immune cells as the exposure variable and their associated genetic variants as instrumental variables. Subsequently, we performed reverse MR analyses with AF as the exposure variable and immune cells as the outcome variable to exclude the interference of reverse causality, to distinguish between primary and secondary effects, and to further elucidate the causal relationship between the immune system and AF. We discovered that membrane proteins on specific immune cells, such as CD25 on memory B cells-which functions as a part of the interleukin-2 receptor-may be risk factors for AF development, with odds ratios of 1.0233 (95% confidence interval: 1.0012-1.0458, P = .0383). In addition, certain immune cell counts, such as the CD4 regulatory T cell Absolute Count, play a protective factor in the development of AF (odds ratio: 0.9513, 95% confidence interval: 0.9165-0.9874; P = .0086). More detailed results are elaborated in the main text. Our MR study has yielded evidence that substantiates a genetically inferred causal association between the immune system and AF. Identifying the risk factors associated with AF is vital to facilitate the development of innovative pharmaceutical treatments.

An altered gut microbiome in pre-eclampsia: cause or consequence

Hypertensive disorders of pregnancy, including pre-eclampsia, are a leading cause of serious and debilitating complications that affect both the mother and the fetus. Despite the occurrence and the health implications of these disorders there is still relatively limited evidence on the molecular underpinnings of the pathophysiology. An area that has come to the fore with regard to its influence on health and disease is the microbiome. While there are several microbiome niches on and within the body, the distal end of the gut harbors the largest of these impacting on many different systems of the body including the central nervous system, the immune system, and the reproductive system. While the role of the microbiome in hypertensive disorders, including pre-eclampsia, has not been fully elucidated some studies have indicated that several of the symptoms of these disorders are linked to an altered gut microbiome. In this review, we examine both pre-eclampsia and microbiome literature to summarize the current knowledge on whether the microbiome drives the symptoms of pre-eclampsia or if the aberrant microbiome is a consequence of this condition. Despite the paucity of studies, obvious gut microbiome changes have been noted in women with pre-eclampsia and the individual symptoms associated with the condition. Yet further research is required to fully elucidate the role of the microbiome and the significance it plays in the development of the symptoms. Regardless of this, the literature highlights the potential for a microbiome targeted intervention such as dietary changes or prebiotic and probiotics to reduce the impact of some aspects of these disorders.

Elucidating the association of obstructive sleep apnea with brain structure and cognitive performance

BACKGROUND

Obstructive sleep apnea (OSA) is a pervasive, chronic sleep-related respiratory condition that causes brain structural alterations and cognitive impairments. However, the causal association of OSA with brain morphology and cognitive performance has not been determined.

METHODS

We conducted a two-sample bidirectional Mendelian randomization (MR) analysis to investigate the causal relationship between OSA and a range of neurocognitive characteristics, including brain cortical structure, brain subcortical structure, brain structural change across the lifespan, and cognitive performance. Summary-level GWAS data for OSA from the FinnGen consortium was used to identify genetically predicted OSA. Data regarding neurocognitive characteristics were obtained from published meta-analysis studies. Linkage disequilibrium score regression analysis was employed to reveal genetic correlations between OSA and related traits.

RESULTS

Our MR study provided evidence that OSA was found to significantly increase the volume of the hippocampus (IVW β (95% CI) = 158.997 (76.768 to 241.227), P = 1.51e-04), with no heterogeneity and pleiotropy detected. Nominally causal effects of OSA on brain structures, such as the thickness of the temporal pole with or without global weighted, amygdala structure change, and cerebellum white matter change covering lifespan, were observed. Bidirectional causal links were also detected between brain cortical structure, brain subcortical, cognitive performance, and OSA risk. LDSC regression analysis showed no significant correlation between OSA and hippocampus volume.

CONCLUSIONS

Overall, we observed a positive association between genetically predicted OSA and hippocampus volume. These findings may provide new insights into the bidirectional links between OSA and neurocognitive features, including brain morphology and cognitive performance.

Exploring the causal relationship between gut microbiota and frailty: a two-sample mendelian randomization analysis

Background

Frailty is a complex geriatric syndrome that seriously affects the quality of life of older adults. Previous observational studies have reported a strong relationship of frailty with the gut microbiota; however, further studies are warranted to establish a causal link. Accordingly, we aimed to conduct a bidirectional Mendelian randomization study to assess the causal relationship between frailty, as measured by the frailty index, and gut microbiota composition.

Methods

Instrumental variables for the frailty index (N = 175, 226) and 211 gut bacteria (N = 18,340) were obtained through a genome-wide association study. A two-sample Mendelian randomization analysis was performed to assess the causal relationship of gut microbiota with frailty. Additionally, we performed inverse Mendelian randomization analyses to examine the direction of causality. Inverse variance weighting was used as the primary method in this study, which was supplemented by horizontal pleiotropy and sensitivity analyses to increase confidence in the results.

Results

Bacteroidia (b = -0.041, SE = 0.017, p = 0.014) and Eubacterium ruminantium (b = -0.027, SE = 0.012, p = 0.028) were protective against frailty amelioration. Additionally, the following five bacteria types were associated with high frailty: Betaproteobacteria (b = 0.049, SE = 0.024, p = 0.042), Bifidobacterium (b = 0.042, SE = 0.016, p = 0.013), Clostridium innocuum (b = 0.023, SE = 0.011, p = 0.036), E. coprostanoligenes (b = 0.054, SE = 0.018, p = 0.003), and Allisonella (b = 0.032, SE = 0.013, p = 0.012). Contrastingly, frailty affected Butyrivibrio in the gut microbiota (b = 1.225, SE = 0.570, p = 0.031). The results remained stable within sensitivity and validation analyses.

Conclusion

Our findings strengthen the evidence of a bidirectional causal link between the gut microbiota and frailty. It is important to elucidate this relationship to optimally enhance the care of older adults and improve their quality of life.

Unraveling the genetic associations between PD-1/PD-L1 and 13 circulating biomarkers linked to physiological and pathological processes

BACKGROUND

Evidence of the genetic interconnectedness between PD-1/PD-L1 and circulating biomarkers related to physiological and pathological processes is largely unclear. Understanding these genetic links is crucial for gaining insights into the underlying mechanisms and potential implications in cancer immunotherapy.

METHODS

To shed light on potential roles of 90 circulating biomarkers in PD-1/PD-L1, we conducted a comprehensive Mendelian randomization (MR) analysis, leveraging genetic data from large-scale genome-wide association studies.

RESULTS

Our results revealed negative associations between EN-RAGE and TRAIL-R2 with PD-1 levels. Additionally, we observed that PD-1 levels were positively associated with TRAIL, VEGF, and ANPEP, indicating their potential role in PD-1 upregulation. Furthermore, our analysis revealed causal associations between several circulating proteins and PD-L1 levels. Thrombomodulin, PSGL-1, TNFSF14, renin, follistatin, β-NGF, KLK6, and MMP-7 demonstrated significant effects on PD-L1 regulation, suggesting their potential inhibitory role in immune checkpoint regulation. Eventually, we confirmed the potential roles of key genes involved in above circulating proteins in influencing the response to immunotherapy.

CONCLUSIONS

Our findings provide valuable evidence of the genetic interconnectedness between PD-1/PD-L1 and circulating proteins related to physiological and pathological processes, shedding light on their potential roles in disease progression and therapeutic interventions.

Exploring the link between gut microbiota and alopecia areata: a two-sample Mendelian randomization analysis

BACKGROUND

While observational studies have suggested a link between gut microbiota diversity and alopecia areata (AA), the causal relationship remains unclear.

METHODS

We leveraged data from the MiBioGen and FinnGen consortiums' Genome-wide association studies (GWAS) encompassing gut microbiota (n = 13,266) and AA (n = 211,428) datasets. A comprehensive Mendelian randomization (MR) and reverse MR approach were employed, utilizing five statistical methods to evaluate causality. Sensitivity analyses were also conducted to corroborate the MR results.

RESULTS

Inverse variance weighted (IVW) analysis indicated a protective effect against AA from Butyricimonas (OR = 0.37, 95% CI: 0.18-0.77, P = 0.01), Enterorhabdus (OR = 0.40, 95% CI: 0.16-0.95, P = 0.04), Eubacterium (xylanophilum group) (OR = 0.36, 95% CI: 0.15-0.84, P = 0.02), and Phascolarctobacterium (OR = 0.37, 95% CI: 0.15-0.91, P = 0.03), while Ruminococcaceae UCG003 posed as a risk factor (OR = 2.79, 95% CI: 1.27-6.14, P = 0.01). Reverse MR showed no significant causal link between AA and gut microbiota, with no significant heterogeneity or horizontal pleiotropy.

CONCLUSIONS

Our analysis suggests probable causality between certain gut microbiota and AA, shedding light on its pathogenesis and potential intervention strategies.

Causal relationships between interleukins, interferons and COVID-19 risk: a Mendelian randomization study

Observational studies have shown close associations between COVID-19 risk and cytokines, especially interleukins (ILs) and interferons (IFNs). However, the causal relationships between ILs, IFNs and COVID-19 were still unclear. To resolve the problem, we conducted a Mendelian randomization analysis between COVID-19 and 47 cytokines, including 35 ILs and 12 IFNs. First, three methods were applied to estimate causal effects by using single nucleotide polymorphisms as instrumental variables (IVs). Subsequently, the MR-Egger method was used to estimate the horizontal pleiotropy of IVs. Finally, sensitivity analyses were applied to assess the robustness of results. As a result, one IFN (IFN-W1) and five ILs (IL-5, IL-6, IL-13, IL-16 and IL-37) were identified to significantly decrease the COVID-19 risk. In contrast, one IFN (IFNG) and five ILs (IL-3, IL-8, IL-27, IL-31 and IL-36β) were found to be significantly associated with an increased risk of COVID-19. In summary, the findings of this study provide insights into potential therapeutic interventions for COVID-19.

Large-scale genome-wide association studies reveal the genetic causal etiology between air pollutants and autoimmune diseases

BACKGROUND

Epidemiological evidence links a close correlation between long-term exposure to air pollutants and autoimmune diseases, while the causality remained unknown.

METHODS

Two-sample Mendelian randomization (TSMR) was used to investigate the role of PM10, PM2.5, NO2, and NOX (N = 423,796-456,380) in 15 autoimmune diseases (N = 14,890-314,995) using data from large European GWASs including UKB, FINNGEN, IMSGC, and IPSCSG. Multivariable Mendelian randomization (MVMR) was conducted to investigate the direct effect of each air pollutant and the mediating role of common factors, including body mass index (BMI), alcohol consumption, smoking status, and household income. Transcriptome-wide association studies (TWAS), two-step MR, and colocalization analyses were performed to explore underlying mechanisms between air pollution and autoimmune diseases.

RESULTS

In TSMR, after correction of multiple testing, hypothyroidism was causally associated with higher exposure to NO2 [odds ratio (OR): 1.37, p = 9.08 × 10-4] and NOX [OR: 1.34, p = 2.86 × 10-3], ulcerative colitis (UC) was causally associated with higher exposure to NOX [OR: 2.24, p = 1.23 × 10-2] and PM2.5 [OR: 2.60, p = 5.96 × 10-3], rheumatoid arthritis was causally associated with higher exposure to NOX [OR: 1.72, p = 1.50 × 10-2], systemic lupus erythematosus was causally associated with higher exposure to NOX [OR: 4.92, p = 6.89 × 10-3], celiac disease was causally associated with lower exposure to NOX [OR: 0.14, p = 6.74 × 10-4] and PM2.5 [OR: 0.17, p = 3.18 × 10-3]. The risky effects of PM2.5 on UC remained significant in MVMR analyses after adjusting for other air pollutants. MVMR revealed several common mediators between air pollutants and autoimmune diseases. Transcriptional analysis identified specific gene transcripts and pathways interconnecting air pollutants and autoimmune diseases. Two-step MR revealed that POR, HSPA1B, and BRD2 might mediate from air pollutants to autoimmune diseases. POR pQTL (rs59882870, PPH4=1.00) strongly colocalized with autoimmune diseases.

CONCLUSION

This research underscores the necessity of rigorous air pollutant surveillance within public health studies to curb the prevalence of autoimmune diseases.

Genetic links between atopy, allergy, and alopecia areata: insights from a Mendelian randomization study

BACKGROUND

Alopecia areata (AA), a prevalent form of autoimmune hair loss, has a not well-defined relationship with atopic and allergic disorders, including eczema, hay fever, and asthma.

OBJECTIVES

This study aims to elucidate the genetic relationship between atopy, allergies, and alopecia areata (AA) using Mendelian randomization. We hypothesize that atopic and allergic conditions contribute to the genetic predisposition of AA.

METHODS

We analyzed extensive genetic data from Genome-wide Association Studies (GWAS) involving over one million individuals. This analysis focused on assessing the genetic correlation between AA and various allergic conditions, including hay fever, eczema, asthma, and allergies to pollen, dust, and cats. The inverse variance weighted method served as our primary analytical tool, complemented by sensitivity analyses to verify the robustness of our results.

RESULTS

Our findings reveal a significant genetic correlation between atopy/allergies and an increased risk of AA. Notably, strong associations were observed for hay fever, eczema, asthma, and specific allergies (pollen, dust, and cats). The sensitivity analyses corroborated these associations, reinforcing the reliability of our primary results.

CONCLUSIONS

This study provides compelling genetic evidence of an association between atopic and allergic conditions and the development of AA. These findings suggest that individuals with such conditions may benefit from enhanced surveillance for early signs of AA.

Causal effect of gut microbiota and diabetic nephropathy: a Mendelian randomization study

BACKGROUND

The interaction of dysbiosis of gut microbiota (GM) with diabetic nephropathy (DN) drew our attention and a better understanding of GM on DN might provide potential therapeutic approaches. However, the exact causal effect of GM on DN remains unknown.

METHODS

We applied two-sample Mendelian Randomization (MR) analysis, including inverse variance weighted (IVW), MR-Egger methods, etc., to screen the significant bacterial taxa based on the GWAS data. Sensitivity analysis was conducted to assess the robustness of MR results. To identify the most critical factor on DN, Mendelian randomization-Bayesian model averaging (MR-BMA) method was utilized. Then, whether the reverse causality existed was verified by reverse MR analysis. Finally, transcriptome MR analysis was performed to investigate the possible mechanism of GM on DN.

RESULTS

At locus-wide significance levels, the results of IVW suggested that order Bacteroidales (odds ratio (OR) = 1.412, 95% confidence interval (CI): 1.025-1.945, P = 0.035), genus Akkermansia (OR = 1.449, 95% CI: 1.120-1.875, P = 0.005), genus Coprococcus 1 (OR = 1.328, 95% CI: 1.066-1.793, P = 0.015), genus Marvinbryantia (OR = 1.353, 95% CI: 1.037-1.777, P = 0.030) and genus Parasutterella (OR = 1.276, 95% CI: 1.022-1.593, P = 0.032) were risk factors for DN. Reversely, genus Eubacterium ventriosum (OR = 0.756, 95% CI: 0.594-0.963, P = 0.023), genus Ruminococcus gauvreauii (OR = 0.663, 95% CI: 0.506-0.870, P = 0.003) and genus Erysipelotrichaceae (UCG003) (OR = 0.801, 95% CI: 0.644-0.997, P = 0.047) were negatively associated with the risk of DN. Among these taxa, genus Ruminococcus gauvreauii played a crucial role in DN. No significant heterogeneity or pleiotropy in the MR result was found. Mapped genes (FDR < 0.05) related to GM had causal effects on DN, while FCGR2B and VNN2 might be potential therapeutic targets.

CONCLUSIONS

This work provided new evidence for the causal effect of GM on DN occurrence and potential biomarkers for DN. The significant bacterial taxa in our study provided new insights for the 'gut-kidney' axis, as well as unconventional prevention and treatment strategies for DN.