Background: Recent studies have suggested an association between gut microbiomes (GMs) and epilepsy. However, the GM taxa identified in different studies are variable. In addition, observational studies cannot indicate causality. Therefore, our study aimed to explore the causal association of GMs with epilepsy and identify the most influential GM taxa.Methods: We conducted a Mendelian randomization (MR) study using summary statistics from genome-wide association studies (GWAS) of 211 GM taxa and epilepsy. The GWAS summary statistics for 211 GM taxa (from phylum to genus level) were generated by the MiBioGen consortium, while the FinnGen consortium provided the GWAS summary statistics for epilepsy. The primary analytical method to assess causality was the inverse-variance weighted (IVW) approach. To complement the IVW method, we also applied four additional MR methods: MR-Egger, weighted median, simple mode, and weighted. In addition, we conducted sensitivity analyses using Cochrane’s Q-test, MR-Egger intercept test, MR-PRESSO global test, and leave-one-out analysis.Results: We evaluated the causal effect of 211 GM taxa (from phylum to genus level) on epilepsy, generalized epilepsy, and focal epilepsy. After using the Bonferroni method for multiple testing correction, Class Betaproteobacteria [odds ratio (OR) = 1.357, 95% confidence interval (CI): 1.126–1.635, p = 0.001] and Order Burkholderiales (OR = 1.336, 95% CI: 1.112–1.606, p = 0.002). In addition, 21 nominally significant causal relationships were also identified. Further, the MR-Egger intercept test and MR-PRESSO global test suggested that our MR analysis was unaffected by horizontal pleiotropy (p > 0.05). Finally, the leave-one-out analysis suggested the robustness of the results.Conclusion: Through the MR study, we analyzed the causal relationship of 211 GM taxa with epilepsy and determined the specific intestinal flora associated with increased epilepsy risk. Our findings may provide helpful biomarkers for disease progression and potential candidate therapeutic targets for epilepsy. In addition, in-depth analysis of large-scale microbiome GWAS datasets based on metagenomics sequencing is necessary for future studies.

Background: Observational studies have shown an association between gastroesophageal reflux disease (GERD) and anxiety disorders/depression. However, these evidences may be influenced by confounding factors. Therefore, our study aimed to determine the causal relationship between GERD and anxiety disorders/depression by conducting a bidirectional Mendelian randomization (MR) study.Methods: We performed a bidirectional MR analysis using summary statistics from genome-wide association studies (GWAS) in European individuals. The inverse-variance weighted (IVW) method was used as the primary analytical method to assess causality. In addition, five additional MR methods [maximum likelihood, MR-Egger, weighted median, robust adjusted profile score (MR-RAPS), and mode-based estimate (MR-MBE)] were performed to supplement the IVW results. Furthermore, several sensitivity analyses were performed to assess heterogeneity, horizontal pleiotropy, and stability. Finally, a multivariable MR (MVMR) analysis was performed to determine the causal relationship by adjusting for potential confounders.Results: MR results of the IVW method indicated that GERD significantly increases the risk of anxiety disorders [odds ratio (OR) = 1.35, 95% confidence interval (CI) 1.15–1.59, P = 2.25 × 10^–4] and depression (OR = 1.32, 95% CI: 1.15–1.52, P = 1.26 × 10^–4). In addition, the MR results of maximum likelihood, MR-Egger, weighted median, MR-RAPS, and MR-MBE remained parallel to the IVW results. Furthermore, sensitivity analysis suggested that the results were robust, with no pleiotropy or heterogeneity detected. Nevertheless, reverse MR analysis showed that anxiety or depression did not increase GERD risk. Finally, MVMR analysis showed that the effect of GERD on increasing the risk of anxiety disorders/depression was independent of confounders.Conclusion: This MR study supports a causal association between GERD and an increased risk of anxiety disorders and depression. Therefore, complementing symptomatic treatment of GERD with psychological assessment and necessary psychological support therapy may help reduce the risk of future anxiety disorders and depression.

Heat stress (HS) is one of the most serious factors to negatively affect the lactation performance of dairy cows. Bovine mammary epithelial cells are important for lactation. It was demonstrated that HS decreases the lactation performance of dairy cows, partly through altering gene expression within bovine mammary epithelial tissue. However, the cellular metabolism mechanisms under HS remains largely unknown. The objective of this study was to determine whether HS induced changes in intracellular metabolites and gene transcription related to amino acid metabolism, amino acid transportation and the mTOR signaling pathway. Immortalized bovine mammary epithelial cell lines (MAC-T cells, n = 5 replicates/treatment) were incubated for 12 h at 37 °C (Control group) and 42 °C (HS group). Relative to the control group, HS led to a greater mRNA expression of heat shock protein genes HSF1, HSPB8, HSPA5, HSP90AB1 and HSPA1A. Compared with the control group, metabolomics using liquid chromatography tandem–mass spectrometry identified 417 differential metabolites with p < 0.05 and a variable importance in projection (VIP) score >1.0 in the HS group. HS resulted in significant changes to the intracellular amino acid metabolism of glutathione, phenylalanine, tyrosine, tryptophan, valine, leucine, isoleucine, arginine, proline, cysteine, methionine, alanine, aspartate and glutamate. HS led to a greater mRNA expression of the amino acid transporter genes SLC43A1, SLC38A9, SLC36A1, and SLC3A2 but a lower mRNA expression of SLC7A5 and SLC38A2. Additionally, HS influenced the expression of genes associated with the mTOR signaling pathway and significantly upregulated the mRNA expression of mTOR, AKT, RHEB, eIF4E and eEF2K but decreased the mRNA expression of TSC1, TSC2 and eEF2 relative to the control group. Compared with the control group, HS also led to greater mRNA expression of the CSN1S2 gene. Overall, our study indicates that bovine mammary epithelial cells may have the ability to resist HS damage and continue milk protein synthesis partly through enhanced intracellular amino acid absorption and metabolism and by activating the mTOR signaling pathway during HS.

Background: Previous studies have shown controversy about whether dried fruit intake is associated with cardiovascular disease. This study aimed to examine the potential causal effect of dried fruit intake on cardiovascular disease by conducting a two-sample Mendelian randomization study.Methods: We used genome-wide association study (GWAS) summary statistics for MR analysis to explore the causal association of dried fruit intake with CVD. The inverse-variance weighted (IVW) method was used as the main analytical method for MR analysis. In addition, the MR-Egger method and the weighted median method were applied to supplement the IVW method. Furthermore, Cochrane’s Q test, MR-Egger intercept test, MR-PRESSO global test, and leave-one-out analysis were used to perform sensitivity analysis.Results: The results from the IVW analysis indicated that dried fruit intake could reduce the risk of heart failure [odds ratio (OR) = 0.6014, 95% confidence interval (CI): 0.4243–0.8522, p-value = 0.0043], total ischemic stroke (OR = 0.4547, 95% CI: 0.2950–0.7010, p-value = 0.0004), and small vessel stroke (OR = 0.3499, 95% CI: 0.1466–0.8349, p-value = 0.0180). In addition, the results of two additional methods (MR Egger and Weighted median) were parallel to the effects estimated by IVW. Furthermore, the sensitivity analysis illustrates that our MR analysis was unaffected by heterogeneity and horizontal pleiotropy. Finally, the results of the leave-one-out method showed the robustness of our MR results.Conclusion: Our study provides evidence for the benefits of dried fruit intake on CVD. Therefore a reasonable consumption of dried fruit may provide primary prevention.

Previous studies have presented conflicting findings regarding the protective effects of circulating sex hormone-binding globulin (SHBG) on ischemic stroke (IS). This study aimed to assess the causal effect of SHBG on IS using Mendelian randomization (MR) analysis and to identify potential mediators. First, the causal effect of SHBG on any IS (AIS), cardioembolic stroke (CES), large artery stroke (LAS), and small vessel stroke (SVS) was assessed by inverse variance weighed (IVW) method. Two additional MR methods (weighted median and MR-Egger) were used to supplement the IVW results. Subsequently, a two-step MR was further performed to assess whether three glycemic profiles [fasting glucose, fasting insulin, and glycated hemoglobin (HbA1c)] and five lipid profiles (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, non-HDL cholesterol, total cholesterol, and triglycerides) mediated the causal effect. Furthermore, Cochrane’s Q test, MR-Egger intercept test, MR-PRESSO global test, and leave-one-out analysis were performed for sensitivity analyses. The IVW results showed that SHBG significantly reduced SVS risk (odds ratio= 0.60, 95% confidence interval: 0.47–0.77, P = 4.60E-05). The weighted median and MR-Egger results were parallel to IVW. However, no significant associations were found between SHBG and AIS, CES, and LAS. Mediation analysis indicated that HbA1c may be involved in SHBG reducing SVS risk. Sensitivity tests demonstrated the reliability of causal estimates. Circulating SHBG levels may decrease SVS risk by lowering HbA1c levels. Therefore, individuals with low circulating SHBG levels should focus on glycemic control to reduce future SVS risk. What is already known on this topic: Ischemic stroke (IS) is a prevailing cause of mortality and disability. Observational studies have produced conflicting results regarding the association between sex hormone-binding globulin (SHBG) and IS. What this study adds: The present Mendelian randomization analysis found that circulating SHBG levels attenuated the risk of small vessel stroke and that this effect may be mediated by lowering glycated hemoglobin levels. Further enrichment analyses suggest that insulin-like growth factor/insulin-like growth factor binding proteins may be involved in this process. However, no causal association was found between SHBG and large vessel stroke or cardioembolic stroke. How this study might affect research, practice, or policy: Individuals with low circulating SHBG levels should focus on glycemic control to reduce the risk of small vessel stroke in the future.