Causal association between inflammatory bowel disease and hidradenitis suppurativa: A two-sample bidirectional Mendelian randomization study

Causal relationship and potential common pathogenic mechanisms between hidradenitis suppurativa and related cancer

BACKGROUND

Hidradenitis suppurativa (HS) is a chronic, inflammatory and common skin disease. Observation studies have reported the association between HS and cancers, however no studies reported whether a causal relationship exists between HS and cancers. This study aimed to explore the causal relationship between HS and differential subtypes of cancers by conducting a bidirectional Mendelian randomization (MR) analysis.

METHOD

Genome-wide association study (GWAS) data related to HS and 16 subtypes of cancers were collected. The inverse variance weighted (IVW) method was primarily applied for our MR analysis, MR-Egger, weighted median, simple mode, and weighted mode methods were used additionally. Heterogeneity, horizontal pleiotropy, and potential outliers were assessed for the MR analysis results. Subsequently, disease-related genes were retrieved from the GeneCards database. To investigate the potential functions of these associated genes, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted.

RESULT

The results of our MR analysis indicated a causal association between HS and pancreatic cancer (PAC). Specifically, HS was found to elevate the risk of developing PAC (odds ratio (OR), 1.074; 95% confidence interval (CI) 1.015-1.135; p = 0.013). Conversely, reverse MR analysis demonstrated that PAC does not exert a causal effect on HS. Furthermore, our findings did not reveal any significant causal relationships between HS and other types of cancer. No evidence of heterogeneity or pleiotropy was identified in the analysis. Additionally, we identified disease-related genes, and subsequent GO and KEGG enrichment analyses indicated that the genes common to both HS and PAC are implicated in pathways associated with immune and inflammatory processes.

CONCLUSION

The results of this study offer novel evidence regarding the causal relationship between HA and PAC. Our Mendelian randomization analysis indicates that HS may have a causal influence on PAC, which could inform the development of improved treatment strategies for patients suffering from HS. However, the underlying mechanisms warrant further exploration.

Evolution of Extraintestinal Manifestations in Patients With Ulcerative Colitis Post-Restorative Proctocolectomy and Ileal Pouch-Anal Anastomosis: A Single-Center Retrospective Study

BACKGROUND AND AIMS

Extraintestinal manifestations (EIMs) are common in patients with ulcerative colitis (UC). However, the prevalence and associated factors of EIMs in UC patients post-restorative proctocolectomy with ileal pouch-anal anastomosis (RPC + IPAA) are not well established.

METHODS

We extracted clinical, demographic, and laboratory data of all UC patients who underwent IPAA surgery and followed up in our comprehensive pouch clinic between 2003 and 2021. EIMs were classified as musculoskeletal, mucocutaneous, ophthalmologic, and hepatic, and their frequency before and after the IPAA surgery was assessed. Univariate and multivariate analyses were performed to detect factors associated with EIMs.

RESULTS

Included were 310 post-IPAA patients with a follow-up of 103.5 (1-250) months. EIMs were documented in 145/310 (46.78%) patients. Of them, 97 (66.9%) had musculoskeletal, 11 (7.59%) had mucocutaneous, 15 (10.34%) had hepatic, and 22 (15.17%) had a combination of 2 EIMs (including 3 ophthalmic cases). Preoperative EIMs were documented in 87/310 (28.1%) patients, and they persisted after the IPAA surgery in 72/87 (82.75%). The preoperative presence of musculoskeletal EIMs (odds ratio [OR]: 8.2, 95% confidence interval [CI]: 4.1-16.7, P = .0001), postoperative chronic pouchitis, and/or Crohn's-like disease of the pouch (OR: 2.2, 95% CI: 1.2-4.1, P = .01), as well as non-Ashkenazi origin (OR: 2.1, 95% CI: 1.1-3.9, P = .01) were associated with the prevalence of postoperative EIMs on a multivariate analysis.

CONCLUSIONS

The EIM rate increases post-IPAA surgery in UC patients, and most preoperative EIMs do not resolve. Awareness of the factors associated with EIMs will enable earlier detection and management for improving patient well-being and quality of life.

Causal Relationship Between Abortion and Endometriosis: A Bidirectional Two-Sample Mendelian Randomization Study

PROBLEM

The relationship between abortion and endometriosis (EMS) has been inconsistent in previous observational studies and remains controversial. We intended to examine the causal relationship between abortion and EMS.

METHODS OF STUDY

We conducted a Mendelian randomization (MR) analysis using genome-wide association study (GWAS) summary statistics, drawing data from the FinnGen database and the UK Biobank. The primary analysis utilized the random-effects inverse variance weighted (IVW) approach, complemented by weighted median, weighted mode, and MR-Egger methods. Comprehensive sensitivity analyses were conducted, encompassing the Cochran's Q statistic for assessing heterogeneity and MR-PRESSO to detect pleiotropy. Additionally, Leave-One-Out (LOO) analysis was conducted to confirm the stability of our results.

RESULTS

The IVW method revealed no statistically significant causal association between various types of abortion and EMS. Specifically, the odds ratios (ORs) were as follows: medical abortion (OR 0.96, 95% CI: 0.78-1.18, p = 0.72), spontaneous abortion (OR 0.99, 95% CI: 0.81-1.21, p = 0.92), and other types of abortions (OR 1.01, 95% CI: 0.99-1.03, p = 0.36), indicating no significant effects on the risk of EMS. Similarly, analysis in the reverse direction showed no significant causal effects of EMS on the likelihood of experiencing any type of abortion, with ORs for medical abortion (0.97, 95% CI: 0.91-1.03, p = 0.33), spontaneous abortion (0.98, 95% CI: 0.92-1.04, p = 0.50), and other abortions (1.30, 95% CI: 0.76-2.23, p = 0.34). Sensitivity analyses supported these findings, demonstrating no evidence of horizontal pleiotropy or significant heterogeneity.

CONCLUSION

Our MR results do not support a causal relationship between abortion and EMS.

Correlations between lichen planus and autoimmune diseases: a Mendelian randomization study

Previous observational studies have found that lichen planus (LP) is associated with autoimmune diseases. To determine the association between LP and 15 autoimmune diseases, we applied the Mendelian randomization (MR) approach, which uses genetic variants as a tool to improve causal inference. We performed a two-sample MR with the genetic instruments identified for 15 autoimmune diseases. Genome-wide association study (GWAS) data was sourced from the IEU Open GWAS database. The instrumental variables (IVs) for LP (1865 cases and 212,242 non-cases) were genetic variations highly associated (P < 5 × 10-6) with LP in the European population. To calculate causal effects, odds ratios (ORs) with 95% confidence intervals (CIs) are employed. MR showed that the genetic risk of psoriasis was positively associated with atopic dermatitis (OR [95%CI] = 0.964[0.936, 0.992], PIVW = 0.013), ankylosing spondylitis (OR [95%CI] = 0.879[0.774, 0.999], PIVW = 0.047) and Type 1 diabetes (OR [95%CI] = 1.074[1.008, 1.145], PIVW = 0.027). These results didn't exhibit horizontal pleiotropy, and "leave-one-out" analysis demonstrated result stability. The MR study indicates a causal relationship between atopic dermatitis, ankylosing spondylitis and Type 1 diabetes in Europe. Further research is necessary to clarify the biological mechanisms that underlie these associations.

Follicular Skin Disorders, Inflammatory Bowel Disease, and the Microbiome: A Systematic Review

Follicular skin disorders, including hidradenitis suppurativa (HS), frequently coexist with systemic autoinflammatory diseases, such as inflammatory bowel disease (IBD) and its subtypes, Crohn's disease and ulcerative colitis. Previous studies suggest that dysbiosis of the human gut microbiome may serve as a pathogenic link between HS and IBD. However, the role of the microbiome (gut, skin, and blood) in the context of IBD and various follicular disorders remains underexplored. Here, we performed a systematic review to investigate the relationship between follicular skin disorders, IBD, and the microbiome. Of the sixteen included studies, four evaluated the impact of diet on the microbiome in HS patients, highlighting a possible link between gut dysbiosis and yeast-exclusion diets. Ten studies explored bacterial colonization and HS severity with specific gut and skin microbiota, including Enterococcus and Veillonella. Two studies reported on immunological or serological biomarkers in HS patients with autoinflammatory disease, including IBD, and identified common markers including elevated cytokines and T-lymphocytes. Six studies investigated HS and IBD patients concurrently. Our systematic literature review highlights the complex interplay between the human microbiome, IBD, and follicular disorders with a particular focus on HS. The results indicate that dietary modifications hold promise as a therapeutic intervention to mitigate the burden of HS and IBD. Microbiota analyses and the identification of key serological biomarkers are crucial for a deeper understanding of the impact of dysbiosis in these conditions. Future research is needed to more thoroughly delineate the causal versus associative roles of dysbiosis in patients with both follicular disorders and IBD.

Causality of inflammatory bowel disease and seborrheic keratosis: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Previous studies have revealed a potential link between inflammatory bowel disease (IBD) and seborrheic keratosis (SK). However, whether this association is causal or confounded remains unknown.

METHODS

We conducted this two-sample Mendelian randomization (TSMR) analysis to clarify bidirectional causality between IBD, including its two primary conditions Crohn's disease (CD) and ulcerative colitis (UC), and SK. The summary genetic data of IBD, CD, UC and SK were obtained from accessible genome-wide association studies (GWAS). This TSMR study was primarily performed using inverse-variance weighted (IVW) method, complemented by MR-Egger, weighted median (WM), Bayesian weighted MR (BWMR), MR-robust adjusted profile score (MR-RAPS), MR-pleiotropy residual sum and outlier (MR-PRESSO), and radial IVW MR analyses with modified second-order weights (IVW [Mod 2nd]) methods. Assessment of sensitivity and identification of potential outliers were subsequently conducted to aid interpretation of results.

RESULTS

The forward MR results showed that IBD [odds ratio (OR) = 1.068, 95% confidence interval (CI) = 1.010-1.129, p = 0.020) and its subtype CD (OR = 1.088, 95%CI = 1.038-1.139, p < 0.001) increased the risk of SK. However, the occurrence of SK could not be affected by UC (OR = 1.090, 95%CI = 0.977-1.216, p = 0.123). In the reverse analysis, no causal relationship between SK and IBD (OR = 0.905, 95%CI = 0.813-1.008, p = 0.069), UC (OR = 0.959, 95%CI = 0.860-1.068, p = 0.443), and CD (OR = 0.933, 95%CI = 0.846-1.029, p = 0.165) was identified.

CONCLUSION

These findings demonstrate that IBD and its subtype CD could increase the incidence of SK in European populations, whereas SK does not affect IBD occurrence.

Hidradenitis suppurativa and cardiovascular diseases: A bidirectional Mendelian randomization study

BACKGROUND

Prior investigation has indicated a link between Hidradenitis suppurativa (HS) and cardiovascular diseases (CVDs), yet the causal relationship (CR) between these conditions remains unresolved.

METHODS

This investigation utilized bidirectional Mendelian randomization (MR) analysis to determine the CR between HS and CVDs. Genetic instruments for both conditions were sourced from genome-wide association studies (GWAS). The GWAS summary data for CVD comprised coronary artery disease (CAD), myocardial infarction (MI), coronary atherosclerosis (CA), ischemic stroke (IS), and chronic heart failure (CHF). Four new approaches were added to the inverse variance weighted (IVW) method for the main analysis: weighted median, weighted MR-Egger, simple mode, and weighted mode. The validity of the causal conclusions was verified by sensitivity tests that included leave-one-out analysis, heterogeneity, and pleiotropy.

RESULTS

HS and CAD (OR = 1.024; 95%CI: 1.002-1.046, P = 0.033), MI (OR = 1.001; 95%CI: 1.000-1.002, P = 0.033), and CA (OR = 1.001; 95%CI: 1.000-1.002, P = 0.022) were identified to have a positive CR, according to the IVW analysis. Conversely, no significant association was identified between HS and either IS or CHF. Furthermore, the bidirectional analysis indicated no reverse causation between these diseases.

CONCLUSION

The findings of this study suggest a potential CR between HS and CAD, MI, and CA. Additional research is warranted to elucidate the biological mechanisms underlying these associations.

A Mendelian randomization study on the causal effects of circulating cytokines on the risk of vitiligo

Background

Accumulating evidence reveals an association between circulating cytokine levels and vitiligo. However, the causal association between circulating cytokine levels and vitiligo remains unrevealed.

Methods

We performed a two-sample Mendelian randomization (MR) analysis using a genome-wide association study of the 41 cytokines dataset, which was conducted with 3 Finnish cohorts (n = 8,293). Vitiligo data were acquired from strictly defined vitiligo data collected by FinnGenbiobank analysis, which included 207,613 European ancestors (131 vitiligo patients, 207,482 controls). The inverse-variance weighted (IVW) method, weighted median (WME), simple model, weighted model, and MR-Egger were used to determine the changes in vitiligo pathogenic cytokine taxa, followed by sensitivity analysis, including horizontal pleiotropy analysis. The MR Steiger test evaluated the strength of a causal association, and the leave-one-out method was used to assess the reliability of the results. The possibility of reverse causality was also investigated using a reverse MR study.

Results

We observed that rising IL-4 levels generated an enhanced probability of vitiligo in IVW (OR 2.72, 95%CI 1.19-6.22, p = 0.018). According to the results of the MR analysis, there were causal links between IL-4 and vitiligo. Results were steady after sensitivity and heterogeneity analyses.

Conclusion

Our research reveals that a genetically determined increased level of circulating IL-4 may be linked to a higher risk of developing vitiligo. The development of innovative treatment approaches (such as tofacitinib or dupilumab) that focus on blocking IL-4 as a novel way of preventing and treating vitiligo is significantly impacted by our findings.

Causal relationship between gut microbiota and hidradenitis suppurativa: a two-sample Mendelian randomization study

Background

Accumulating evidence suggests that alterations in gut microbiota composition are associated with the hidradenitis suppurativa (HS). However, the causal association between gut microbiota and HS remain undetermined.

Methods

We performed a bidirectional two-sample Mendelian randomization (MR) analysis using genome-wide association study summary data of gut microbiota and hidradenitis suppurativa from the MiBioGen consortium which concluded 18,340 individuals analyzed by the MiBioGen Consortium, comprising 211 gut microbiota. HS data were acquired from strictly defined HS data collected by FinnGenbiobank analysis, which included 211,548 European ancestors (409 HS patients, 211,139 controls). The inverse variance weighted method (IVW), weighted median (WME), simple model, weighted model, weighted median, and MR-Egger were used to determine the changes of HS pathogenic bacterial taxa, followed by sensitivity analysis including horizontal pleiotropy analysis. The MR Steiger test evaluated the strength of a causal association and the leave-one-out method assessed the reliability of the results. Additionally, a reverse MR analysis was carried out to seek for possible reverse causality.

Results

By combining the findings of all the MR steps, we identified four causal bacterial taxa, namely, Family XI, Porphyromonadaceae, Clostridium innocuum group and Lachnospira. The risk of HS might be positively associated with a high relative abundance of Clostridium innocuum group (Odds ratio, OR 2.17, p = 0.00038) and Lachnospira (OR 2.45, p = 0.017) but negatively associated with Family XI (OR 0.67, p = 0.049) and Porphyromonadaceae (OR 0.29, p = 0.014). There were no noticeable outliers, horizontal pleiotropy, or heterogeneity. Furthermore, there was no proof of reverse causation found in the reverse MR study.

Conclusion

This study indicates that Clostridium innocuum group and Lachnospira might have anti-protective effect on HS, whereas Family XI and Porphyromonadaceae might have a protective effect on HS. Our study reveals that there exists a beneficial or detrimental causal effect of gut microbiota composition on HS and offers potentially beneficial methods for therapy and avoidance of HS.

Association between viral infections and glioma risk: a two-sample bidirectional Mendelian randomization analysis

BACKGROUND

Glioma is one of the leading types of brain tumor, but few etiologic factors of primary glioma have been identified. Previous observational research has shown an association between viral infection and glioma risk. In this study, we used Mendelian randomization (MR) analysis to explore the direction and magnitude of the causal relationship between viral infection and glioma.

METHODS

We conducted a two-sample bidirectional MR analysis using genome-wide association study (GWAS) data. Summary statistics data of glioma were collected from the largest meta-analysis GWAS, involving 12,488 cases and 18,169 controls. Single-nucleotide polymorphisms (SNPs) associated with exposures were used as instrumental variables to estimate the causal relationship between glioma and twelve types of viral infections from corresponding GWAS data. In addition, sensitivity analyses were performed.

RESULTS

After correcting for multiple tests and sensitivity analysis, we detected that genetically predicted herpes zoster (caused by Varicella zoster virus (VZV) infection) significantly decreased risk of low-grade glioma (LGG) development (OR = 0.85, 95% CI: 0.76-0.96, P = 0.01, FDR = 0.04). No causal effects of the other eleven viral infections on glioma and reverse causality were detected.

CONCLUSIONS

This is one of the first and largest studies in this field. We show robust evidence supporting that genetically predicted herpes zoster caused by VZV infection reduces risk of LGG. The findings of our research advance understanding of the etiology of glioma.