Age at menarche and ischemic heart disease: An update mendelian randomization study

Exploring the causal relationship between inflammatory cytokines and myasthenia gravis: A two-way Mendelian randomization study

BACKGROUND

Based on previous research, it is well-established that myasthenia gravis (MG) is linked to chronic inflammation. However, the exact nature of the relationship between inflammatory factors and the development of MG remains unclear. Consequently, the objective of this study is to explore whether alterations in the levels of inflammatory factors, as influenced by genetic factors, are associated with the occurrence of MG. This will be achieved through a two-sample Mendelian randomization (MR) analysis.

METHODS

We conducted a bidirectional Mendelian randomization (MR) study utilizing genetic data from genome-wide association studies (GWAS), encompassing 1873 MG cases and 36,370 individuals of European ancestry as controls. Data on inflammatory cytokines were obtained from GWAS data of 8293, healthy participants. The inverse variance-weighted (IVW) method was primarily employed to investigate the causal relationship between exposure and outcome. Additionally, various sensitivity analysis methods such as MR-Egger, weighted median, simple mode, weighted mode, and MR-PRESSO were applied to strengthen the reliability of the results. Through these rigorous approaches, we extensively examined the relationship between inflammatory factors and MG; however, further research is required to establish the specific causal relationship.

RESULTS

After applying Bonferroni correction, the genetic predictions revealed a significant correlation between Monokine induced by gamma interferon (MIG) and MG (OR: 1.09, 95 % CI: 1.04-1.14; P = 0.0006). Furthermore, there were preliminary findings indicating a positive genetic association between Eotaxin and interleukin-2 receptor antagonist (IL-2ra) with MG (OR: 0.81, 95 % CI: 0.66-0.99, P = 0.044; OR: 0.80, 95 % CI: 0.68-0.94, P = 0.008). Reverse MR analysis provided initial evidence of associations between MIP1α, GROa, IL-13, TRAIL, IL-2ra, and IL-1ra with the development of MG. No indications of pleiotropy or heterogeneity among genetic variants were observed (P > 0.05).

CONCLUSION

This study uncovers a new connection between inflammatory cytokines and MG, shedding light on potential factors contributing to the development of the disease. Elevated levels of Eotaxin and IL-2ra are associated with a higher risk of MG, while indicating that MIG, MIP1α, GROa, IL-13, TRAIL, IL-2ra, and IL-1ra may be elevated as a result of MG, Especially MIG. These findings suggest that targeting and regulating specific inflammatory factors could offer promising avenues for the treatment and prevention of MG.

Unraveling the Causal Relationship Between Blood Metabolites and Acne: A Metabolomic Mendelian Randomization Study

BACKGROUND

Acne is a common skin disorder that may be linked to metabolic dysfunction. However, the causal impact of blood metabolites on acne has not been thoroughly investigated.

METHODS

We performed a metabolome-wide Mendelian randomization (MR) analysis on 486 blood metabolites and acne using a genome-wide association dataset. The study included preliminary inverse-variance weighted (IVW) analysis, multivariable MR analysis, linkage disequilibrium score (LDSC) analysis, and colocalization analysis, along with reverse MR to address potential reverse causation.

RESULTS

Our analysis identified 12 metabolites significantly associated with acne. LDSC analysis revealed a genetic correlation between nonanoylcarnitine and acne. Colocalization analysis confirmed shared genetic variants, and metabolic pathway analysis implicated the arginine biosynthesis pathway and the selenocompound metabolism pathway in the development of acne.

CONCLUSION

This study offers a comprehensive understanding of the causal relationships between plasma metabolites and acne. The findings provide insights into potential biomarkers and therapeutic targets for acne treatment, underscoring the need for further research.

Age at Menarche Is Associated With Leg-Length Components Among the Adolescent Girls in West Bengal, India

BACKGROUND

The relationship between early age at menarche (AAM) and body height (HT), including its different segments has not been extensively studied among non Western populations. Lengths of the lower (distal) part of the leg, such as knee HT (KH) and tibial length (TbL), are considered to be sensitive indicators of living conditions during early growth and development. Life history theory predicts that within a survival challenge the growth of vital parts of the body shall be prioritized over less essential parts. The present study hypothesized that earlier age at menarche would be associated with shorter tibial length in resource constrained settings.

AIM

To investigate the potential associations of menarcheal age with HT, KH, TbL, and other linear components of HT among the Bengalee schoolgirls aged 10-13 years.

METHODS

Among the 208 girls aged 10-13 years, menarcheal status and age at menarche were determined by status quo and retrospective methods, respectively. Lower leg length was represented by two measures, KH and the supracutaneous measure of TbL. The differences in HT, sitting HT (SH), total leg length (LL), thigh length (TL), KH, and TbL, between pre-menarcheal-(PMG) and post-menarcheal girls (POMG), as well as between earlier menarcheal-(EMG) and later menarcheal girls (LMG), were assessed by student t-test and analysis of covariance.

RESULTS

The POMG were heavier, taller and had higher adiposity than their PMG peers, without showing any significant age-difference. HT, knee HT, TbL, and TbL to HT ratio showed significant differences between the EMG and LMG. The EMG showed lower values for all of those measures and the strongest difference was observed for TbL. However, there were no significant differences in SH and SHR between EMG and LMG.

CONCLUSIONS

The study indicated a possible effect of early AAM on growth of distal body parts in a resource poor socioeconomic condition. Further studies on the relationship between growth and AAM among different populations living in different socio-ecological conditions could be worth conducting.

The causal relationship between bacterial pneumonia and diabetes: a two-sample mendelian randomization study

BACKGROUND

Previous observational studies have established the high prevalence of bacterial pneumonia in diabetic patients, which in turn leads to increased mortality. However, the presence of a causal connection between bacterial pneumonia and diabetes remains unobserved.

METHODS

We chose genome-wide significant (Ρ < 1 × 10-5 and Ρ < 1 × 10-6) and independent (r2 < 0.001) single-nucleotide polymorphisms (SNPs) as instrumental variables (IVs) to proceed a bidirectional two-sample MR study. The extracted SNPs explored the relationship between bacterial pneumonia and diabetes by Inverse variance weighted (IVW), MR-Egger, and weighted median methods. In addition, we conducted the Heterogeneity test, the Pleiotropy test, MR-presso and the Leave-one-out (LOO) sensitivity test to validate the reliability of results.

RESULTS

In an MR study with bacterial pneumonia as an exposure factor, four different types of diabetes as outcome. It was observed that bacterial pneumonia increases the incidence of GDM (OR = 1.150 (1.027-1.274, P = 0.011) and T1DM (OR = 1.277 (1.024-1.531), P = 0.016). In the reverse MR analysis, it was observed that GDM (OR = 1.112 (1.023-1.201, P = 0.009) is associated with an elevated risk of bacterial pneumonia. However, no significant association was observed bacterial pneumonia with T1DM and other types of diabetes (P > 0.05).

CONCLUSION

This study utilizing MR methodology yields robust evidence supporting a bidirectional causal association between bacterial pneumonia and GDM. Furthermore, our findings suggest a plausible causal link between bacterial pneumonia and T1DM.

Molecular mechanisms underlying Tao-Hong-Si-Wu decoction treating hyperpigmentation based on network pharmacology, Mendelian randomization analysis, and experimental verification

CONTEXT

Hyperpigmentation, a common skin condition marked by excessive melanin production, currently has limited effective treatment options.

OBJECTIVE

This study explores the effects of Tao-Hong-Si-Wu decoction (THSWD) on hyperpigmentation and to elucidate the underlying mechanisms.

MATERIALS AND METHODS

We employed network pharmacology, Mendelian randomization, and molecular docking to identify THSWD's hub targets and mechanisms against hyperpigmentation. The Cell Counting Kit-8 (CCK-8) assay determined suitable THSWD treatment concentrations for PIG1 cells. These cells were exposed to graded concentrations of THSWD-containing serum (2.5%, 5%, 10%, 15%, 20%, 30%, 40%, and 50%) and treated with α-MSH (100 nM) to induce an in vitro hyperpigmentation model. Assessments included melanin content, tyrosinase activity, and Western blotting.

RESULTS

ALB, IL6, and MAPK3 emerged as primary targets, while quercetin, apigenin, and luteolin were the core active ingredients. The CCK-8 assay indicated that concentrations between 2.5% and 20% were suitable for PIG1 cells, with a 50% cytotoxicity concentration (CC50) of 32.14%. THSWD treatment significantly reduced melanin content and tyrosinase activity in α-MSH-induced PIG1 cells, along with downregulating MC1R and MITF expression. THSWD increased ALB and p-MAPK3/MAPK3 levels and decreased IL6 expression in the model cells.

DISCUSSION AND CONCLUSION

THSWD mitigates hyperpigmentation by targeting ALB, IL6, and MAPK3. This study paves the way for clinical applications of THSWD as a novel treatment for hyperpigmentation and offers new targeted therapeutic strategies.

Body Mass Index and Hypertension as Mediators of the Association Between Age at Menarche and Subclinical Atherosclerosis: A Sex-Specific Mendelian Randomization Analysis

BACKGROUND

Early age at menarche (AAM) has been associated with a higher risk of carotid artery intima-media thickness (cIMT), an indicator of subclinical vascular disease, albeit the mechanisms underlying this association remain elusive. A better understanding of the relationship between AAM, modifiable cardiometabolic risk factors, and subclinical atherosclerosis may contribute to improved primary prevention and cardiovascular disease treatment. We aimed to investigate the putative causal role of AAM on cIMT, and to identify and quantify the potentially mediatory effects of cardiometabolic risk factors underlying this relationship.

METHODS AND RESULTS

We conducted linkage disequilibrium score regression analyses between our exposure of interest, AAM, our outcome of interest, cIMT and potential mediators of the AAM-cIMT association to gauge cross-trait genetic overlap. We considered as mediators the modifiable anthropometric risk factors body mass index (BMI), systolic blood pressure (SBP), lipid traits (total cholesterol, triglycerides, high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol), and glycemic traits (fasting glucose). We then leveraged the paradigm of Mendelian randomization to infer causality between AAM and cIMT, and to identify whether cardiometabolic risk factors served as potential mediators of this effect. Our analyses showed that genetically predicted AAM was inversely associated with cIMT, BMI, SBP, and triglycerides, and positively associated with high-density lipoprotein, low-density lipoprotein, and total cholesterol. We showed that the effect of genetically predicted AAM on cIMT may be partially mediated through BMI (20.1% [95% CI, 1.4% to 38.9%]) and SBP (13.5% [95% CI, 0.5%-26.6%]). Our cluster-specific Mendelian randomization revealed heterogeneous causal effect estimates of age at menarche on BMI and SBP.

CONCLUSIONS

We highlight supporting evidence for a potential causal association between earlier AAM and cIMT, and almost one third of the effect of AAM on cIMT may be mediated by BMI and SBP. Early intervention aimed at lowering BMI and hypertension may be beneficial in reducing the risk of developing subclinical atherosclerosis due to earlier age at menarche.

The effect of metabolism-related lifestyle and clinical risk factors on digestive system cancers in East Asian populations: a two-sample Mendelian randomization analysis

Metabolic factors play a critical role in the development of digestive system cancers (DSCs), and East Asia has the highest incidence of malignant tumors in the digestive system. We performed a two-sample Mendelian randomization analysis to explore the associations between 19 metabolism-related lifestyle and clinical risk factors and DSCs, including esophageal, gastric, colorectal, hepatocellular, biliary tract, and pancreatic cancer. The causal association was explored for all combinations of each risk factor and each DSC. We gathered information on the instrumental variables (IVs) from various sources and retrieved outcome information from Biobank Japan (BBJ). The data were all from studies of east Asian populations. Finally, 17,572 DSCs cases and 195,745 controls were included. Our analysis found that genetically predicted alcohol drinking was a strong indicator of gastric cancer (odds ratio (OR) = 0.95; 95% confidence interval (CI): 0.93-0.98) and hepatocellular carcinoma (OR = 1.11; 95% CI: 1.05-1.18), whereas coffee consumption had a potential protective effect on hepatocellular carcinoma (OR = 0.69; 95% CI: 0.53-0.90). Triglyceride was potentially associated with a decreased risk of biliary tract cancer (OR = 0.53; 95% CI: 0.34-0.81), and uric acid was associated with pancreatic cancer risk (OR = 0.59; 95% CI: 0.37-0.96). Metabolic syndrome (MetS) was associated with esophageal and gastric cancer. Additionally, there was no evidence for a causal association between other risk factors, including body mass index, waist circumference, waist-to-hip ratio, educational levels, lipoprotein cholesterol, total cholesterol, glycine, creatinine, gout, and Graves' disease, and DSCs. The leave-one-out analysis revealed that the single nucleotide polymorphism (SNP) rs671 from the ALDH2 gene has a disproportionately high contribution to the causal association between alcohol drinking and gastric cancer and hepatocellular carcinoma, as well as the association between coffee consumption and hepatocellular carcinoma. The present study revealed multiple metabolism-related lifestyle and clinical risk factors and a valuable SNP rs671 for DSCs, highlighting the significance of metabolic factors in both the prevention and treatment of DSCs.

Mitochondrial DNA copy number and cancer risks: A comprehensive Mendelian randomization analysis

Mitochondrial DNA plays a critical role in the pathophysiology of cancer. However, the associations between mitochondrial DNA copy number (mtDNA-CN) and cancer risk are controversial. Mendelian randomization (MR) analyses were performed using three independent instrumental variables (IVs) to explore potential associations between mtDNA-CN and 20 types of cancer. The three sets of IVs were primarily obtained from participants in the UK Biobank and the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium using different methods. The outcome data of cancers were investigated using summary statistics from the FinnGen cohort. The potential causal associations were evaluated using the MR-Egger regression, weighted median, inverse-variance weighted (IVW), and weighted mode methods. The robustness of IVW estimates was validated using leave-one-out sensitivity analysis. Additionally, a meta-analysis was conducted to pool results from three sets of IVs. The results revealed that genetically predicted mtDNA-CN was not associated with cancer risk (odds ratio = 1.02; 95% confidence interval: 0.95-1.10). Subgroup analyses indicated no causal association between mtDNA-CN and breast, lung, prostate, skin, colorectal, gastric, liver, cervical uteri, esophageal, thyroid, bladder, pancreas, kidney, corpus uteri, ovary, brain, larynx, and anus cancers. It was observed that mtDNA-CN was associated with lip, oral cavity, and testis cancers. However, these results should be interpreted with caution because a small number of patients with lip and oral cavity or testis cancers were included. The comprehensive MR analysis demonstrated that mtDNA-CN is not a suitable biomarker for tumor risk assessment.

Mitochondrial DNA copy number is associated with Crohn's disease: a comprehensive Mendelian randomization analysis

Mitochondrial DNA plays a critical role in the pathophysiological process of inflammation. However, the relationship between mitochondrial DNA copy number (mtDNA-CN) and inflammatory bowel diseases (IBD) remains poorly understood. We conducted a comprehensive Mendelian randomization (MR) using three instrumental variables (IVs) to explore the causal associations between mtDNA-CN and IBD, including Crohn's disease (CD), ulcerative colitis (UC). MR-Egger regression, weighted median, inverse-variance weighted (IVW), and weighted mode methods were used to evaluate the potential causal associations. The robustness of the IVW estimates was determined using the leave-one-out sensitivity test. A meta-analysis was conducted to pool the results from the three sets of IVs. Upon analysis, the findings of the current study revealed that genetically predicted mtDNA-CN was not associated with IBD (CD + UC) and UC. The results of MR analyses between mtDNA-CN and CD risk were inconsistent by using three sets of IVs. After a meta-analysis, we found that genetically predicted mtDNA-CN was associated with CD risk (odds ratio = 2.09; 95% confidence interval: 1.37-3.18). This finding was also confirmed by multivariable MR analyses and remained robust when tested with the leave-one-out sensitivity test. In conclusion, genetically predicted mtDNA-CN was found to be associated with CD risk. Therefore, mtDNA levels in the blood could potentially be used as a marker for CD risk assessment. Further studies are needed to elucidate the underlying mechanisms and validate the results of this study.

Health outcomes of age at menarche in European women: a two-sample Mendelian randomization study

BACKGROUND

Observational studies have shown an association between age at menarche (AAM) and the risk of gynecological diseases. However, the causality cannot be determined due to residual confounding.

METHODS

We conducted a Mendelian randomization (MR) study to evaluate the causal effect of AAM on several gynecological diseases, including endometriosis, female infertility, pre-eclampsia or eclampsia, uterine fibroids, breast cancer, ovarian cancer, and endometrial cancer. Single nucleotide polymorphisms were used as genetic instruments. The inverse variance weighted method was used as the primary approach and several other MR models were conducted for comparison. Cochran's Q test, Egger's intercept test, and leave-one-out analysis were conducted for sensitivity analysis. Radial MR analysis was conducted when detecting the existence of heterogeneity.

RESULTS

After Bonferroni correction and thorough sensitivity analysis, we observed a robust causal effect of AAM on endometrial cancer (odds ratio: 0.80; 95% confidence interval: 0.72-0.89; P = 4.61 × 10-5) and breast cancer (odds ratio: 0.94; 95% confidence interval: 0.90-0.98; P = .003). Sensitivity analysis found little evidence of horizontal pleiotropy. The inverse variance weighted method also detected weak evidence of associations of AAM with endometriosis and pre-eclampsia or eclampsia.

CONCLUSIONS

This MR study demonstrated a causal effect of AAM on gynecological diseases, especially for breast cancer and endometrial cancer, which indicates AAM might be a promising index to use for disease screening and prevention in clinical practice. Key messages What is already known on this topic - Observational studies have reported associations between age at menarche (AAM) and a variety of gynecological diseases but the causality has not been determined. What this study adds - This Mendelian randomization study demonstrated that AAM causally affects the risk of breast cancer and endometrial cancer. How this study might affect research, practice, or policy - The findings of our study imply that AAM could be a candidate marker for early screening of populations at higher risk of breast cancer and endometrial cancer.