Objective To evaluate the potential causal relationship between asthma and the risk of gastroesophageal reflux disease (GERD) using a two-sample Mendelian randomization study. Methods A large sample of genome-wide association study was used to summarize the data, and the genetic loci [single nucleotide polymorphisms (SNPs)] closely related to asthma were selected as instrumental variables, and Mendelian randomization analysis was conducted by inverse variance weighting, weighted median and MR-Egger method, respectively. At the same time, the multi-effect of MR-Egger was detected and the sensitivity analysis was carried out by Leave-one-out method to ensure the robustness of the results. Results A total of 77 SNPs closely related to asthma were selected as instrumental variables. The results of inverse variance weighted analysis showed a significant positive correlation between asthma and the occurrence of gastroesophageal reflux disease [odds ratio (OR)=1.044, 95% confidence interval (CI) (1.006, 1.083), P=0.024]. Weighted median results showed similar causality [OR=1.075, 95%CI (1.021, 1.133), P=0.006]. The MR-Egger regression results showed that there was a positive correlation between asthma and GERD, but there was no statistical significance [OR=1.080, 95%CI (0.983, 1.187), P=0.115]. The heterogeneity test results showed that there was no heterogeneity in the causal relationship between asthma and GERD (P>0.05). The results of the horizontal pleiotropy test showed that there was no horizontal pleiotropy in SNPs (P>0.05). The results of the retention test showed that no SNPs with significant impact on the results were detected. Conclusion There is a positive causal relationship between asthma and GERD.
Objective To analyze the causal relationship between gut microbiota and childhood asthma based on Mendelian randomization (MR). Methods The human gut microbiota dataset was downloaded from the MiBioGen database, and 196 known bacterial groups (9 phyla, 16 classes, 20 orders, 32 families, and 119 genera) were retained as exposure factors. Single nucleotide polymorphisms (SNPs) that were strongly correlated with exposure factors and independent of each other were selected as effective instrumental variables. A childhood asthma dataset with 3 025 patients and 135 449 controls was downloaded from the genome-wide association studies database as the outcome variable. Two-sample MR analysis was performed using inverse variance weighted, weighted median, MR-Egger, weighted model and simple model methods, respectively. The causal association between gut microbiota and childhood asthma was evaluated by odds ratio (OR). Sensitivity analysis was performed by leave-one-out method. Horizontal pleiotropy was tested by MR-Egger intercept test and MR-PRESSO global test, and Cochran’s Q test was used for heterogeneity. Results A total of 15 out of 196 gut microbiota groups were found to have a causal association (P<0.05) with the risk of childhood asthma, with a total of 181 SNPs included in the analysis. Inverse variance weighted analysis showed that Mollicutes [OR=1.42, 95% confidence interval (CI) (1.10, 1.83), P=0.007], Escherichia-Shigella [OR=1.39, 95%CI (1.02, 1.90), P=0.036], Oxalobacter [OR=1.30, 95%CI (1.10, 1.54), P=0.002], Ruminococcaceae UCG-009 [OR=1.34, 95%CI (1.09, 1.64), P=0.006] and Tenericutes [OR=1.42, 95%CI (1.10, 1.83), P=0.007] were significantly positively correlated with childhood asthma. Actinobacteria [OR=0.76, 95%CI (0.58, 0.99), P=0.042], Bifidobacteriaceae [OR=0.76, 95%CI (0.58, 0.98), P=0.035], Eubacterium nodatum group [OR=0.81, 95%CI (0.70, 0.94), P=0.007], Bifidobacterales [OR=0.76, 95%CI (0.58, 0.98), P=0.035] and Actinobacteria [OR=0.74, 95%CI (0.56, 0.99), P=0.040] were negatively correlated with childhood asthma. In addition, the results of leave-one-out sensitivity analysis were stable, MR-Egger intercept test and MR-PRESSO global test showed no horizontal pleiotropy, and Cochran’s Q test showed no heterogeneity. Conclusions There is a causal relationship between gut microbiota and childhood asthma. Mollicutes, Escherichia-Shigella, Oxalobacter, Ruminococcaceae UCG-009 and Tenericutes may increase the risk of childhood asthma. Actinobacteria, Bifidobacteriaceae, Eubacterium nodatum group, Bifidobacterales and Actinobacteria can reduce the risk of childhood asthma.
ObjectiveTo explore the potential causal relationship between 91 inflammatory factors and the risk of lung cancer (LC). MethodsBy extracting related data of inflammatory factors and LC and its subtypes from public databases of genome-wide association studies (GWAS), bidirectional, repeated, multivariable Mendelian randomization (MR) and subgroup MR methods were used for analysis. The inverse variance weighted method was mainly used for causal inference, and a series of sensitivity analyses were applied to verify the strength of the results. ResultsHigher levels of CD5, interleukin-18 (IL-18), and oncostatin-M (OSM) were causally associated with a lower risk of LC, while nerve growth factor-β (NGF-β) and S100 calcium-binding protein A12 (S100A12) were associated with an increased risk of LC. Subgroup MR analysis results showed that IL-18 had a causal relationship with a reduced risk of lung adenocarcinoma, while NGF-β and S100A12 had a causal relationship with an increased risk of lung adenocarcinoma; CD5 and OSM had a causal relationship with a reduced risk of lung squamous cell carcinoma; NGF-β had a causal relationship with an increased risk of small cell lung cancer. ConclusionFive inflammatory factors, including CD5, IL-18, OSM, NGF-β, and S100A12 have a causal correlation with the risk of LC, providing potential targets for early screening of LC patients and development of therapeutic drugs.