Causal effects of gut microbiota on erectile dysfunction: a two-sample Mendelian randomization study

Identification of biomarkers and potential drug targets for esophageal cancer: a Mendelian randomization study

Esophageal cancer (EC) is a common and deadly malignancy of the digestive system. Currently, effective treatments for EC are limited and patient prognosis remains poor. In this study, we utilized Mendelian Randomization (MR) to identify potential drug targets for EC by analyzing proteins linked to the disease risk. A total of 734 plasma proteins and 4,479 druggable genes were obtained from recent studies, and two-sample MR analyses were conducted to investigate causal relationships between these proteins and EC. The cis-pQTL data of the proteins was analyzed after filtering. The inverse variance weighted (IVW) method was the primary analytical approach in MR analysis. Steiger filtering, heterogeneity and pleiotropy tests, Summary-data-based Mendelian Randomization (SMR) analysis, and Bayesian co-localization analysis were implemented to consolidate the results further. Moreover, drugs corresponding to the identified proteins were found in the DrugBank database. Five proteins HPSE, ST3GAL1, CEL, KLK13, and GNRH2 were identified as highly associated with EC. HPSE and GNRH2 showed protective effects with odds ratios (OR) of 0.80 (95% confidence interval [CI], 0.70-0.92) and 0.73 (95% CI 0.54-0.98), respectively. In contrast, increased expression of ST3GAL1(OR, 1.37; 95% CI 1.04-1.82), CEL (OR, 1.27; 95% CI 1.08-1.49), and KLK13 (OR, 1.22; 95% CI 1.04-1.42) were all associated with a higher risk of EC. In addition, the HPSE protein showed moderate colocalization with EC [coloc.abf-posterior probability of hypothesis 4 (PPH4) = 0.637]. Furthermore, the sensitivity analyses indicated no heterogeneity or pleiotropy. Therefore, these findings present promising drug targets for EC and deserve further clinical investigation.

Mendelian randomization analyses reveal causal relationships between chronic psychological stress and risk of erectile dysfunction

Background

The association between psychological stress and erectile dysfunction (ED) has been reported, but the causality of different types of stressors on ED is poorly understood.

Aim

This study aims to investigate the causal relationship between various forms of psychological stress and ED through Mendelian randomization (MR).

Methods

Several genome-wide association study (GWAS) datasets related to chronic psychological stress were used in this study for the identification of instrumental variables. Concurrently, a genome-wide association studies database provided the ED outcome data containing 6175 ED patients and 217 630 controls. The MR-Egger, inverse variance weighting (IVW), weighted median, and maximum likelihood methods were applied to conduct the MR study and IVW was taken as the primary criterion.

Outcomes

Mendelian randomization analyses revealed that financial difficulties were associated with a heightened risk of ED, whereas the absence of stressors was linked to a decreased risk.

Results

Among the various types of psychological stressors analyzed, financial difficulties were found to significantly increase the risk of ED (P = .022, OR = 4.343, 95%CI = 1.240-15.216). In contrast, other stressors did not significantly elevate the risk of ED. Furthermore, the absence of these stressors was associated with a reduced risk of ED (P = .009, OR = 0.211, 95% CI = 0.066-0.681).

Clinical implications

This study emphasizes the enormous impact of psychological stress, especially financial hardship, in increasing the risk of ED.

Strengths and limitations

This study is the first to employ MR analysis to investigate the causal relationship between various stressors and ED. However, this study did not consider the influence of non-genetic factors such as living environment and lifestyles.

Conclusion

Psychological stress, particularly financial difficulties, can increase the risk of ED, while the absence of such stressors appears to be protective. Consequently, it is imperative to enhance medical education and awareness among economically disadvantaged populations and to address the detrimental effects of adverse lifestyles.

The Role of Gut Microbiota Dysbiosis in Erectile Dysfunction: From Pathophysiology to Treatment Strategies

Erectile dysfunction (ED) is a prevalent male sexual disorder characterized by the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance. While its etiology is multifactorial, encompassing vascular, neurological, hormonal, and psychological components, emerging evidence suggests a significant role for gut microbiota dysbiosis in its development. The gut microbiota influences various metabolic, inflammatory, and neuropsychological processes critical to erectile function. Dysbiosis can lead to systemic inflammation, endothelial dysfunction, hormonal imbalances, and altered neurotransmitter production, all of which are key factors in ED pathogenesis. This narrative review synthesizes current research on the association between gut microbiota alterations and ED, highlighting specific bacterial taxa implicated in ED through mechanisms involving inflammation, metabolic disturbances, and hormonal regulation. This review explores potential mechanisms linking gut microbiota and ED, including pro-inflammatory cytokines, gut barrier integrity disruption, metabolic disorders, psychological factors via the gut-brain axis, and hormonal regulation. Furthermore, the gut microbiota offers promising avenues for developing non-invasive biomarkers and therapeutic interventions such as probiotics, prebiotics, dietary modifications, and fecal microbiota transplantation. Future research should focus on longitudinal studies, mechanistic explorations, and clinical trials to validate these findings and translate them into clinical practice. Understanding the interplay between the gut microbiota and erectile function could unveil novel diagnostic biomarkers and pave the way for innovative treatments targeting the microbiota, ultimately improving men's sexual and overall health.

The causal relationship between gut microbiota and 2 neoplasms, malignant and benign neoplasms of bone and articular cartilage: A two-sample Mendelian randomization study

Previous research has demonstrated a close connection between the development of bone neoplasms and variations in the abundance of specific gut microbiota. It remains unclear, however, how the gut microbiota and bone neoplasms are causally related. Hence, in our study, we aim to clarify this relationship between gut microbiota and 2 neoplasms, malignant neoplasm of bone and articular cartilage (MNBAC) and benign neoplasm of bone and articular cartilage (BNBAC), by employing a two-sample Mendelian randomization (MR) approach. In this study, single nucleotide polymorphisms (SNPs) from genome-wide association studies-pooled data related to bone neoplasms and gut microbiota abundance were evaluated. The inverse variance weighted was employed as the major method for assessing the aforementioned causal relationship. Furthermore, the horizontal multiplicity was evaluated utilizing the Mendelian randomization pleiotropy residual sum and outlier and the MR-Egger intercept test. Finally, inverse MR analysis was performed to assess reverse causality. Inverse variance weighted results indicate a potential genetic relationship between 4 gut microbiota and MNBAC, and 3 gut microbiota and BNBAC. On the one hand, Eubacterium eligens group (OR = 0.16, 95% CI = 0.04-0.67, P = .01), Odoribacter (OR = 0.23, 95% CI = 0.06-0.84, P = .03), Slackia (OR = 0.35, 95% CI = 0.13-0.93, P = .04), and Tyzzerella3 (OR = 0.44, 95% CI = 0.24-0.82, P = .01) exhibited a protective effect against MNBAC. On the other hand, of the 3 gut microbes identified as potentially causally related to BNBAC, Oscillibacter (OR = 0.79, 95% CI = 0.63-0.98, P = .03) and Ruminococcus torques group (OR = 0.62, 95% CI = 0.39-0.98, P = .04) were regarded as protective strains of B, while Eubacterium ruminantium group (OR = 1.24, 95% CI = 1.04-1.47, P = .02) was considered to be a risk factor for increasing the incidence of BNBAC. Additionally, the bone neoplasms were not found to have a reverse causal relationship with the above 7 gut microbiota taxa. Four gut microbiota showed causal effects on MNBAC, and 3 gut microbiota demonstrated causality in BNBAC, providing insights into the design of future interventions to reduce the burden of neoplasms.

Inflammatory cytokines may mediate the causal relationship between gut microbiota and male infertility: a bidirectional, mediating, multivariate Mendelian randomization study

Introduction

Studies have shown that the gut microbiota is associated with male infertility (MI). However, their causal relationship and potential mediators need more evidence to prove. We aimed to investigate the causal relationship between the gut microbiome and MI and the potential mediating role of inflammatory cytokines from a genetic perspective through a Mendelian randomization approach.

Methods

This study used data from genome-wide association studies of gut microbes (Mibiogen, n = 18, 340), inflammatory cytokines (NFBC1966, FYPCRS, FINRISK 1997 and 2002, n=13, 365), and male infertility (Finngen, n=120, 706) to perform two-way Mendelian randomization (MR), mediated MR, and multivariate MR(MVMR) analyses. In this study, the inverse variance weighting method was used as the primary analysis method, and other methods were used as supplementary analysis methods.

Results

In the present study, two gut microbes and two inflammatory cytokines were found to have a potential causal relationship with MI. Of the two gut microorganisms causally associated with male infertility, Anaerotruncus increased the risk of male infertility (odds ratio = 1.81, 95% confidence interval = 1.18-2.77, P = 0.0062), and Bacteroides decreased the risk of male infertility (odds ratio = 0.57, 95% confidence interval = 0.33-0.96, P = 0.0363). In addition, of the two inflammatory cytokines identified, hepatocyte growth factor(HGF) reduced the risk of male infertility (odds ratio = 0.50, 95% confidence interval = 0.35-0.71, P = 0.0001), Monocyte chemotactic protein 3 (MCP-3) increased the risk of male infertility (odds ratio = 1.28, 95% confidence interval = 1.03-1.61, P = 0.0039). Mediated MR analysis showed that HGF mediated the causal effect of Bacteroides on MI (mediated percentage 38.9%). Multivariate MR analyses suggest that HGF may be one of the pathways through which Bacteroides affects MI, with other unexplored pathways.

Conclusion

The present study suggests a causal relationship between specific gut microbiota, inflammatory cytokines, and MI. In addition, HGF may mediate the relationship between Bacteroides and MI.

Dissecting the association between gut microbiota and hypertrophic scarring: a bidirectional Mendelian randomization study

Hypertrophic scars affect a significant number of individuals annually, giving rise to both cosmetic concerns and functional impairments. Prior research has established that an imbalance in the composition of gut microbes, termed microbial dysbiosis, can initiate the progression of various diseases through the intricate interplay between gut microbiota and the host. However, the precise nature of the causal link between gut microbiota and hypertrophic scarring remains uncertain. In this study, after compiling summary data from genome-wide association studies (GWAS) involving 418 instances of gut microbiota and hypertrophic scarring, we conducted a bidirectional Mendelian randomization (MR) to investigate the potential existence of a causal relationship between gut microbiota and the development of hypertrophic scar and to discern the directionality of causation. By utilizing MR analysis, we identified seven causal associations between gut microbiome and hypertrophic scarring, involving one positive and six negative causal directions. Among them, Intestinimonas, Ruminococcus2, Barnesiella, Dorea, Desulfovibrio piger, and Ruminococcus torques act as protective factors against hypertrophic scarring, while Eubacterium rectale suggests a potential role as a risk factor for hypertrophic scars. Additionally, sensitivity analyses of these results revealed no indications of heterogeneity or pleiotropy. The findings of our MR study suggest a potential causative link between gut microbiota and hypertrophic scarring, opening up new ways for future mechanistic research and the exploration of nanobiotechnology therapies for skin disorders.

Potential causal association between aspirin use and erectile dysfunction in European population: a Mendelian randomization study

Background

Aspirin, as one of the most commonly used drugs, possesses a broad spectrum of therapeutic applications. Presently, the potential association between aspirin usage and the risk elevation of erectile dysfunction (ED) remains inconclusive. The objective of this study employing two-sample Mendelian randomization (MR) was to clarify the causal impact of aspirin use on the risk of ED.

Methods

This study incorporated two sets of Genome-Wide Association Study (GWAS) summary statistics, one for aspirin use (46,946 cases and 286,635 controls) and another for ED (6,175 cases and 217,630 controls) in individuals of European ancestry. The inverse-variance weighted (IVW) method was employed as the primary approach, supplemented by MR-Egger, weighted median, weighted mode, and simple mode to estimate the causal effect of aspirin usage on the risk of ED development. To assess pleiotropy, the MR-PRESSO global test and MR-Egger regression were used. Cochran's Q test was adopted to check heterogeneity, and the leave-one-out analysis was performed to confirm the robustness and reliability of the results.

Results

The causal association between genetically inferred aspirin use and ED was found by using inverse variance weighted (OR = 20.896, 95% confidence interval = 2.077-2.102E+2, P = 0.010). The sensitivity analysis showed that no pleiotropy and heterogeneity was observed. Furthermore, the leave-one-out analysis demonstrated that the findings were not significantly affected by any instrumental variables.

Conclusion

The results of this study highlighted the significance of aspirin use as a predisposing factor for ED and provided further evidence supporting the causal association between aspirin utilization and ED within European populations.