Genetic Associations Between IL-6 and the Development of Autoimmune Arthritis Are Gender-Specific

The Genetic Background of Ankylosing Spondylitis Reveals a Distinct Overlap with Autoimmune Diseases: A Systematic Review

Background: Ankylosing Spondylitis (AS) is a rare autoinflammatory disorder affecting 0.1-1.4% of the population, with increasing recognition over the past 20 years. Although the specific causes of AS remain unclear, the presence of the HLA-B27 gene is associated with increased risk, though only 1-5% of carriers develop the disease. Despite extensive research, no definitive lab tests exist, and many patients are diagnosed years after symptom onset. Methods: In the present study, in order to investigate the disease's genetic background in correlation with autoimmune diseases, a metanalysis has been performed following PRISMA guidelines using Scopus and PubMed publications towards extracting single-nucleotide polymorphisms (SNPs) of high importance for the disease. Moreover, the polymorphisms have been annotated and analyzed using information from several databases, including PubMed, LitVar2, ClinVar, and Gene Ontology. Results: From 1940 screened titles and abstracts, 57,909 studies were selected, with 539 meeting the inclusion criteria. The genetic background of AS is described through 794 genetic variants, of which 76 SNPs are directly associated with AS (Classes A and B), predominantly located in intronic regions. ERAP1 and IL23R emerged as key genes implicated in AS, while chromosomes 1, 2, and 5 accumulated the most associated SNPs. Functional enrichment revealed strong associations with immune regulation and interleukin signaling pathways, particularly IL6 and IL10 signaling. IL-6 promotes inflammation in AS, while IL-10 tries to suppress it, acting as an anti-inflammatory cytokine. Of the 78 AS-related SNPs, 16 were unique to AS, while 66 were common to autoimmune diseases, especially rheumatoid arthritis (RA) and psoriasis (PsO), suggesting genetic overlap between these diseases. Conclusions: This study creates a comprehensive genetic map of AS-associated SNPs, highlighting key pathways and genetic overlap with autoimmune diseases. These findings contribute to understanding disease mechanisms and could guide therapeutic interventions, advancing precision medicine in AS management.

Sex differences in biomarkers and biologic mechanisms in psoriatic diseases and spondyloarthritis

Psoriasis and spondyloarthritis (SpA), including psoriatic arthritis (PsA), are immune-mediated inflammatory conditions that affect the skin and musculoskeletal system. Males and female patients with psoriatic disease and SpA exhibit differences in clinical presentation, disease progression, and treatment response. The underlying biological mechanisms driving these sex differences remain poorly understood. This review explores the current evidence on sex-related differences in biomarkers and biological pathways in psoriasis, PsA, and SpA. While no conclusive sex-specific biomarkers have been validated, this review highlights several sex-related differences in biomarkers and biological pathways, including differences in bone turnover markers, IL-23/IL-17 pathway activity, pro-inflammatory cytokines, and cardio-metabolic profiles that may partially contribute to the clinical differences observed between male and female patients. Sex hormones may contribute to the altered bone metabolism and immune regulation in females. To effectively identify and validate sex-specific biomarkers, there is a need to prioritize sex as a biological variable in future research. Adopting such an approach should enhance more personalized therapeutic strategies and improve management for male and female patients with psoriatic disease and SpA.

CDC42: unlocking a novel therapeutic target for primary sclerosing cholangitis through Mendelian randomization

OBJECTIVES

This study seeks to identify new drug targets for Primary Sclerosing Cholangitis (PSC), a condition currently lacking effective treatment, to improve survival without transplantation.

METHODS

We obtained summary statistics for 2,888 druggable genes and PSC from the eQTLGen Consortium and the FinnGen consortium, respectively. Through two-sample Mendelian randomization using the Inverse Variance Weighted (IVW) method, we identified genes associated with PSC at a False Discovery Rate (FDR) < 0.05. Further validation came from colocalization and Summary-data-based Mendelian Randomization (SMR) analyses, confirming the reliability of our results.

RESULTS

Five druggable genes were causally associated with PSC at FDR < 0.05. Subsequent colocalization and SMR analyses further confirmed that higher levels of CDC42 in plasma were associated with an increased risk of PSC (IVW method: Odds Ratio 1.319, 95% Confidence Interval 1.182-1.471, P = 6.85E-07, FDR = 0.002).

CONCLUSIONS

Our research pioneered the identification of CDC42 as a target for slowing PSC progression. Our research not only uncovers a possible drug target but also provides direction for the development of therapeutics for PSC.

Genetic correlation between genes targeted by lipid-lowering drugs and venous thromboembolism: A drug-target Mendelian randomization study

Dyslipidemia has been established as a potential risk factor for venous thromboembolism (VTE) in several observational studies. Statins and novel lipid-modifying agents are being explored for their potential in VTE prevention, encompassing deep vein thrombosis (DVT), and pulmonary embolism (PE). Nonetheless, conclusive evidence supporting the effectiveness remains uncertain. Without definitive proof, the current recommendation of lipid-lowering drugs (LLDs) for preventing VTE, either primarily or secondarily, is not support. An investigation into the impact of 8 classes of LLDs on VTE was conducted using a drug-target Mendelian randomization approach. The drug categories examined included 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), apolipoprotein B, proprotein convertase subtilisin/kexin type 9, Niemann-Pick C1-like 1, lipoprotein lipase (LPL), angiopoietin-like 3, apolipoprotein C3 (APOC3), and peroxisome proliferator-activated receptor alpha. Leveraging genetic variants situated proximate to or within drug-target genes linked with low-density lipoprotein and triglycerides, we acted as proxies for LLDs. The UK Biobank study was the source of data on VTE, PE, and DVT of lower extremities (LEDVT). We employed the inverse-variance weighted method for the core analysis in Mendelian randomization, complemented by sensitivity analysis to investigate horizontal pleiotropy and heterogeneity. Employing genetic proxies to inhibit HMGCR revealed a notable correlation with reduced LEDVT risk (odds ratio [OR]: 0.995, 95% CI: 0.992-0.998, P = .002), VTE (OR: 0.994, 95% CI: 0.988-1.000, P = .033), but a no significant association with PE (OR: 1.000, 95% CI: 0.994-1.002, P = .246). The suppression of APOB was linked with an elevated risk of experiencing LEDVT (OR: 1.002, 95% CI: 1.001-1.004, P = .006), VTE (OR: 1.005, 95% CI: 1.002-1.007, P < .001), and PE (OR: 1.002, 95% CI: 1.000-1.004, P = .031). Similarly, the activation of LPL was associated with increased risks for VTE (OR: 1.003, 95% CI: 1.001-1.005, P = .003) and PE (OR: 1.003, 95% CI: 1.002-1.005, P < .001). Additionally, the inhibition of APOC3 was linked to a higher DVT risk (OR: 1.002, 95% CI: 1.000-1.004, P = .038). Research has shown that HMGCR, out of 8 lipid-lowering drug-targets evaluated, exhibited a significant correlation with VTE and LEDVT, highlighting its potential as an effective target for the treatment or prevention of these conditions. In contrast, APOB, LPL, and APOC3 each contribute to an increased risk of VTE, PE, and LEDVT in various degrees, pharmacovigilance for VTE, PE, and LEDVT risk among users of APOB inhibitors, LPL activation, and APOC3 inhibitors may be warranted.

Unveiling the mystery: Investigating the debate surrounding mitochondrial DNA copy number and Sjögren syndrome using Mendelian randomization analysis

Numerous studies have investigated the relationship between mitochondrial DNA (mtDNA) copy number and Sjögren syndrome (SS). However, the conclusions remain inconclusive, with conflicting findings. The genome-wide association study summary statistics for mtDNA copy number were obtained from 2 sources: a cohort of 465,809 White individuals from the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium and the UK Biobank, and a dataset of 395,718 UK Biobank participants. Additionally, we obtained 2 sets of genome-wide association study summary statistics for SS through datasets from FinnGen and the UK Biobank, involving a total of 809,836 participants. Furthermore, we conducted a two-sample bidirectional Mendelian randomization analysis, primarily utilizing the inverse variance weighted method, complemented by 4 other validation methods, to explore the association between mtDNA copy number and SS. Following our comprehensive investigation, no discernible causal relationship was identified between mtDNA copy number and SS in either the training or validation cohorts (inverse variance weighted, P  > .05). Similarly, the reverse Mendelian randomization analysis yielded negative results (inverse variance weighted, P  > .05). Furthermore, all analyses indicated an absence of horizontal pleiotropy or heterogeneity. Our analysis revealed no causal relationship between mtDNA copy number and SS.

Unveiling the truth: Pathogen infections linked to miscarriage: A STROBE-Compliant Mendelian randomization study

Miscarriage represents a prevalent yet insufficiently studied adverse pregnancy outcome. The definitive causal links between various pathogens and miscarriage remain to be established. To investigate the causal connections between pathogen infections and miscarriage, we utilized a two-sample bidirectional Mendelian randomization (MR) analysis. We sourced genome-wide association studies data on pathogen infections from the UK Biobank, which included serological markers for infectious diseases and comprehensive whole-genome genetic information from approximately 10,000 individuals. Additionally, genome-wide association studies data on miscarriages were collected from 3 distinct European populations for our analysis. The MR analysis was primarily conducted using the inverse variance weighted method, complemented by Bayesian weighted MR and the weighted median method for robustness. To ensure the reliability of our findings, we performed heterogeneity and pleiotropy tests, leave-one-out sensitivity analyses, and a meta-analysis. Our extensive research has identified a causal association between miscarriage and infections by several human herpesviruses (HHV-1, HHV-3, HHV-4, HHV-6, and HHV-7), polyomaviruses (BK, JC, and Merkel cell polyomaviruses), and Chlamydia trachomatis (inverse variance weighted, P < .05). Notably, a meta-analysis of the integrated data highlighted the particularly high accuracy and consistency of the association with Merkel cell polyomavirus. Our MR analysis has clarified the causal relationships between specific pathogen infections and miscarriage, providing a critical foundation for the prevention and treatment of this adverse pregnancy outcome.

PWAS Hub for exploring gene-based associations of common complex diseases

PWAS (proteome-wide association study) is an innovative genetic association approach that complements widely used methods like GWAS (genome-wide association study). The PWAS approach involves consecutive phases. Initially, machine learning modeling and probabilistic considerations quantify the impact of genetic variants on protein-coding genes' biochemical functions. Secondly, for each individual, aggregating the variants per gene determines a gene-damaging score. Finally, standard statistical tests are activated in the case-control setting to yield statistically significant genes per phenotype. The PWAS Hub offers a user-friendly interface for an in-depth exploration of gene-disease associations from the UK Biobank (UKB). Results from PWAS cover 99 common diseases and conditions, each with over 10,000 diagnosed individuals per phenotype. Users can explore genes associated with these diseases, with separate analyses conducted for males and females. For each phenotype, the analyses account for sex-based genetic effects, inheritance modes (dominant and recessive), and the pleiotropic nature of associated genes. The PWAS Hub showcases its usefulness for asthma by navigating through proteomic-genetic analyses. Inspecting PWAS asthma-listed genes (a total of 27) provide insights into the underlying cellular and molecular mechanisms. Comparison of PWAS-statistically significant genes for common diseases to the Open Targets benchmark shows partial but significant overlap in gene associations for most phenotypes. Graphical tools facilitate comparing genetic effects between PWAS and coding GWAS results, aiding in understanding the sex-specific genetic impact on common diseases. This adaptable platform is attractive to clinicians, researchers, and individuals interested in delving into gene-disease associations and sex-specific genetic effects.

Decoding skin mysteries: Unveiling the link between microbiota and keloid scars through a Mendelian randomization study

The cause of keloids remains unclear, but studies suggest a link between skin microbiota and keloid formation. However, the causal relationship has not been confirmed. This study utilized Genome-Wide Association Studies (GWAS) data from 2 population-based German cohorts, comprising a total of 1656 skin samples. To bolster the reliability of our results, we incorporated GWAS data from 3 keloid cohorts, encompassing 2555 patients and 870,556 controls (GWAS ID: keloid1, ebi-a-GCST90018874; keloid2, bbj-a-131; keloid3, ebi-a-GCST90018654). Subsequently, we employed bidirectional 2-sample Mendelian randomization (MR) analysis to probe the causal relationship between the variables. The primary method employed was the inverse-variance weighted (IVW) method, supported by heterogeneity analysis, horizontal pleiotropy testing, outlier detection, and "leave-one-out" sensitivity analysis. By synthesizing the results from 3 groups of MR analyses, we discovered a negative causal association between a.ASV063 [Finegoldia (unc.)] located on the volar forearm and keloid disease (IVW (keloid1) odds ratio (OR): 0.939, 95% confidence interval (CI): 0.886-0.994, P = .032; IVW (keloid2) OR: 0.897, 95% CI: 0.813-0.990, P = .031; IVW (keloid3) OR: 0.900, 95% CI: 0.825-0.981, P = .017). Similarly, a negative causal relationship may also exist between the genus: Bacteroides from the antecubital fossa and keloid disease (IVW (keloid1) OR: 0.928, 95% CI: 0.884-0.973, P = .002; IVW (keloid2) OR: 0.891, 95% CI: 0.820-0.968, P = .007; IVW (keloid3) OR: 0.918, 95% CI: 0.849-0.992, P = .030). Additionally, no reverse causation was found, with all analyses showing no signs of horizontal pleiotropy or heterogeneity. This study offers new insights for the prevention and treatment of keloids.

Rheumatoid arthritis reduces the risk of colorectal cancer through immune inflammation mediation

There is a close relationship between immune-mediated inflammation and cancer, and there is still controversy over whether rheumatoid arthritis (RA) increases the risk of malignancy. We first used Mendelian randomization (MR) analysis to explore the potential causal relationship between RA and pan-cancer. And verify the effect of immune-mediated inflammation on cancer through intermediate MR analysis. Then we extracted the standardized incidence rate of malignancy in RA patients relative to the general population through large-scale meta-analysis. Finally, we performed pan-cancer analysis on the RA related genes obtained from MR analysis. And perform immune related analysis on key genes to reveal the association between RA and malignancy. The MR analysis demonstrated a negative correlation between RA and pan-cancer (p = 0.008). Autoimmune traits were the main mediating variable for the causal relationship between RA and pan-cancer. Based on the results of the meta-analysis, we validated that RA reduces the risk of developing colorectal cancer (SIR = 0.69, 95% CI 0.53-0.85). Pan-cancer analysis also showed that high expression of RA related genes was negatively correlated with colon adenocarcinoma. IL6R was the gene with the highest correlation among them, and its correlation with immune cells was higher in colorectal cancer than in other malignancy. Our MR study provides evidence that RA was associated with reduced risk of colorectal cancer. This effect is caused by immune-mediated inflammation, with IL6R being a key regulatory gene.

Age at Natural Menopause, Reproductive Lifespan, and the Risk of Late-Onset Psoriasis and Psoriatic Arthritis in Women: A Prospective Cohort Study

Although a peak incidence of psoriasis in women aged around 60 years has been observed, the link between reproductive lifespan and late-onset psoriatic diseases is underexplored. This study aims to elucidate the association between reproductive lifespan and the risk of late-onset psoriasis and psoriatic arthritis (PsA). Utilizing the UK Biobank data, we conducted a prospective cohort study in postmenopausal women without baseline psoriatic diseases. The exposure variables included age at natural menopause (ANM) and duration from menarche to menopause, termed reproductive years. The outcome variables were incident psoriasis and PsA. We employed Cox regression analysis, factoring in polygenic risk scores for psoriatic diseases and recognized risk factors. We found that later ANM and longer reproductive years were significantly associated with decreased risks of late-onset psoriasis and PsA in a dose-dependent manner (P<.05). ANM after age 55 years led to a 34 and 46% risk reduction in late-onset psoriasis and PsA, respectively, compared with ANM before age 45 years (P<.001). The population-attributable risks of ANM were 17.4% for late-onset psoriasis and 21.6% for PsA. In conclusion, reproductive lifespan, with its inherent homeostasis, plays a pivotal yet overlooked role in late-onset psoriatic diseases. Investigations into estrogen-centric causes and sex-specific interventions are imperative.

Causal effect of interleukin (IL)-6 on blood pressure and hypertension: A mendelian randomization study

To examine whether circulating interleukin-6 (IL-6) levels (CirIL6) have a causal effect on blood pressure using Mendelian randomization (MR) methods. We used data from genome-wide association studies (GWAS) of European ancestry to obtain genetic instruments for circulating IL-6 levels and blood pressure measurements. We applied several robust MR methods to estimate the causal effects and to test for heterogeneity and pleiotropy. We found that circulating IL-6 had a significant positive causal effect on systolic blood pressure (SBP) and pulmonary arterial hypertension (PAH), but not on diastolic blood pressure (DBP) or hypertension. We found that as CirIL6 genetically increased, SBP increased using Inverse Variance Weighted (IVW) method (for ukb-b-20175, β = 0.082 with SE = 0.032, P = 0.011; for ukb-a-360, β = 0.075 with SE = 0.031, P = 0.014) and weighted median (WM) method (for ukb-b-20175, β = 0.061 with SE = 0.022, P = 0.006; for ukb-a-360, β = 0.065 with SE = 0.027, P = 0.014). Moreover, CirIL6 may be associated with an increased risk of PAH using WM method (odds ratio (OR) = 15.503, 95% CI, 1.025-234.525, P = 0.048), but not with IVW method. Our study provides novel evidence that circulating IL-6 has a causal role in the development of SBP and PAH, but not DBP or hypertension. These findings suggest that IL-6 may be a potential therapeutic target for preventing or treating cardiovascular diseases and metabolic disorders. However, more studies are needed to confirm the causal effects of IL-6 on blood pressure and to elucidate the underlying mechanisms and pathways.

Investigation of the causal relationship between Interleukin-6 signaling and gastrointestinal tract cancers: A Mendelian randomization study

BACKGROUND

Observational studies indicate that interleukin-6(IL-6) has been associated with gastrointestinal tract cancers. However, the causal association is still confusing. Thus, we aimed to putative the causality between IL-6 signaling and gastrointestinal tract cancers.

METHODS

We conducted a two-sample Mendelian randomization analysis to assess the causal effects. Two groups of IL-6 signaling-related single nucleotide polymorphisms were chosen from two Genome-wide association studies. Summary-level data for gastrointestinal tract cancers including esophageal, gastric, and colorectal cancer, were obtained from the FinnGen consortium and UK Biobank study. We also performed survival analysis to explore the prognostic value of IL-6 in gastrointestinal tract cancers.

RESULTS

Genetically predicted plasma sIL6R level, which inhibits IL-6 Signaling, was associated with a reduced risk of gastric cancer in FinnGen. In the combined analysis of the two sources, genetically predicted sIL6R was associated with a decreased risk of gastric cancer (OR = 0.943, 95%CI: 0.904,0.983, p = 0.006). Survival analysis results indicated the prognostic value of IL-6 in gastric cancer.

CONCLUSIONS

These results present evidence indicating that genetically-determined reduced IL-6 signaling lowers the risk of gastric cancer, which may provide potential prevention and therapeutic strategies for gastric cancer. Additionally, IL-6 may be a prognostic biomarker for gastric cancer.

Sex bias in immune response: it is time to include the sex variable in studies of autoimmune rheumatic diseases

Healthy females and males differ in their immune cell composition and function and females generally mount stronger immune response than males and are much more susceptible to autoimmune rheumatic diseases. Females differ from males in sex hormones, and X-chromosome genes. Sex hormones affect immune cells and responses, and may induce epigenetic DNA changes. The importance of X-chromosome genes is exemplified in men with the Klinefelter syndrome (47,XXY) who have an additional X-chromosome and develop systemic lupus erythematosus(SLE) as frequently as women. X-chromosome contains genes critical for the immune response, such as FOXP3, toll-like receptor(TLR)7, TLR8, CD40 Ligand, IL2RG, IL9R, BTK, and others. Whereas one X-chromosome in females is randomly inactivated early in embryonic development, around 25% of X-linked genes escape inactivation and result in more X-linked gene dosage in females. We use two key female-biased autoimmune rheumatic diseases, SLE and systemic sclerosis, to review differences in immune response, and clinical manifestations between females and males. The inclusion of sex variable in research will facilitate precision medicine and optimal patient outcome.

Mendelian randomization study on causal association of IL-6 signaling with pulmonary arterial hypertension

BACKGROUND

A recent Mendelian randomization (MR) did not support an effect of the lead interleukin-6 receptor (IL-6 R) variant on risk of pulmonary arterial hypertension (PAH). Thus, we used two sets of genetic instrumental variants (IVs) and publicly available PAH genome-wide association studies (GWAS) to reassess the genetic causal link between IL-6 signaling and PAH.

METHODS

Six independent IL-6 signaling and 34 independent soluble IL-6 receptor (sIL-6 R) genetic IVs from recent MR reports and PAH GWAS including 162,962 European individuals were used to perform this two-sample MR study.

RESULTS

We found that as IL-6 signaling genetically increased, the risk of PAH reduced using IVW (odds ratio [OR] = 0.023, 95% confidence interval [CI]: 0.0013-0.393; p = .0093) and weighted median (OR = 0.033, 95% CI: 0.0024-0.467; p = .0116). Otherwise, as sIL-6 R genetically increased, the risk of PAH increased using IVW (OR = 1.34, 95% CI: 1.16-1.56; p = .0001), weighted median (OR = 1.36, 95% CI: 1.10-1.68; p = .005), MR-Egger (OR = 1.43, 95% CI: 1.05-1.94; p = .03), and weighted mode (OR = 1.35, 95% CI for OR: 1.12-1.63; p = .0035).

CONCLUSION

Our analysis suggested the causal link between genetically increased sIL-6 R and increased risk of PAH and between genetically increased IL-6 signaling and reduced risk of PAH. Thus, higher sIL-6 R levels may be a risk factor for patients with PAH, whereas higher IL-6 signaling may be a protective factor for patients with PAH.

No evidence of genetic causal association between sex hormone-related traits and systemic lupus erythematosus: A two-sample Mendelian randomization study

OBJECTIVE

Previous studies have demonstrated an association between sex hormone-related traits and systemic lupus erythematosus (SLE). However, because of the difficulties in determining sequential temporality, the causal association remains elusive. In this study, we used two-sample Mendelian randomization (MR) to explore the genetic causal associations between sex hormone-related traits and SLE.

METHODS

We used a two-sample MR to explore the causal association between sex hormone-related traits and SLE. The summarized data for sex hormone-related traits (including testosterone, estradiol (E2), sex hormone-binding globulin (SHBG), and bioavailable testosterone (BT)) originated from large genome-wide association studies (GWASs) of European descent. Aggregated data for SLE were derived from the FinnGen consortium (835 cases and 300,162 controls). Random-effects inverse-variance weighted (IVW), MR-Egger, weighted median, simple mode, weighted mode, and fixed-effects IVW methods were used for the MR analysis. Random-effects IVW was the primary method used to analyze the genetic causal association between sex hormone-related traits and SLE. Heterogeneity of the MR results was detected using the IVW Cochran's Q estimates. The pleiotropy of MR results was detected using MR-Egger regression and the MR pleiotropy residual sum and outlier (MR-PRESSO) test. Finally, leave-one-out analysis was performed to determine whether MR results were affected by a single single-nucleotide polymorphism (SNP).

RESULTS

Random-effects IVW as the primary method showed that testosterone (odds ratio (OR), 0.87; 95% confidence interval (CI), 0.41-1.82; P = 0.705), E2 (OR, 0.95; 95% CI, 0.73-1.23; P = 0.693), SHBG (OR, 1.25; 95% CI, 0.74-2.13; P = 0.400), and BT (OR, 0.99; 95% CI, 0.67-1.47; P = 0.959) had no potential causal association with SLE. The MR-Egger, weighted median, simple mode, weighted mode, and fixed-effects IVW methods all indicated consistent results. The results of the MR-Egger regression showed that there was no pleiotropy in our MR analysis (P > 0.05). The IVW Cochran's Q estimates showed that the MR analysis results of E2, SHBG, and BT on SLE had no heterogeneity (P > 0.05), but testosterone and SLE had heterogeneity (P < 0.05). The leave-one-out analysis confirmed that a single SNP did not affect the MR results.

CONCLUSIONS

Our MR analysis demonstrated that genetically predicted testosterone, E2, SHBG, and BT levels were not associated with SLE risk, but the roles of other non-genetic pathways cannot be ruled out. Key Points • This is the first MR study to explore the causal association of sex hormone-related traits with SLE. • No evidence to support causal associations between sex hormone-related traits and SLE. • Our MR analysis may provide novel insights into the causal association between sex hormone-related traits and SLE risk.

Mendelian Randomization Studies in Psoriasis and Psoriatic Arthritis: A Systematic Review

Psoriasis (PSO) and psoriatic arthritis (PSA) are inflammatory diseases with complex genetic and environmental contributions. Although studies have identified environmental and clinical associations with PSO/PSA, causality is difficult to establish. Mendelian randomization (MR) employs the random assortment of genetic alleles at birth to evaluate the causal impact of exposures. We systematically reviewed 27 MR studies in PSO/PSA examining health behaviors, comorbidities, and biomarkers. Exposures, including smoking, obesity, cardiovascular disease, and Crohn's disease, were causal for PSO and PSA, whereas PSO was causally associated with several comorbidities. These findings provide insights that can guide preventive counseling and precision medicine.

Mendelian Randomization Study on Causal Association of IL-6With Breast Cancer

BACKGROUND

Previous studies have shown an important role of interleukin 6 (IL-6) in the progression and metastasis of breast cancer. The present 2-sample Mendelian randomization (MR) study aimed to identify the genetic causal link between IL-6 and breast cancer.

MATERIAL AND METHODS

IL-6-signaling and its negative regulator soluble IL-6 receptor (sIL-6R) genetic instruments were chosen from 2 large-scale genome-wide association studies (GWAS) of 204,402 and 3,301 European individuals, respectively. GWAS for breast cancer (14,910 cases and 17,588 controls of European ancestry) was used to evaluate the effect of IL-6-signaling- or sIL-6R-associated genetic instrumental variants on breast cancer risk by performing a 2-sample MR study.

RESULTS

As IL-6-signaling genetically increased, breast cancer risk increased based on weighted median (odds ratio [OR] = 1.396, 95% confidence interval [CI]: 1.008-1.934, P = .045) and inverse variance weighted (IVW) (OR = 1.370, 95% CI: 1.032-1.819, P = .030). Otherwise, as sIL-6R genetically increased, the risk of breast cancer decreased based on weighted median (OR = 0.975, 95% CI: 0.947-1.004, P = .097) and IVW (OR = 0.977, 95% CI: 0.956-0.997, P = .026).

CONCLUSION

Our analysis suggests a causal link between a genetically-linked increase in IL-6-signaling and increase in the risk of breast cancer. Thus, inhibition of IL-6 may be a valuable biological indicator for risk assessment, prevention, and treatment of patients with breast cancer.

Genetically downregulated Interleukin-6 signalling is associated with a lower risk of frailty

BACKGROUND

numerous studies point towards a critical role of Interleukin 6 (IL-6) pathway in frailty pathogenesis yet the causal relationship between the two remains elusive.

METHODS

we selected genetic variants near the IL-6 receptor locus (IL-6R) associated with reduced C-reactive protein (CRP) levels, a downstream effector of IL-6 pathway, and we used them as genetic proxies of IL-6 signalling downregulation. We then performed a two-sample Mendelian randomisation (MR) to investigate the association with frailty status, as defined by the Frailty Index (FI) in 11,171 individuals from the Hellenic Longitudinal Investigation of Ageing and Diet (HELIAD) study. MR analysis was repeated after excluding depression or cognition-related FI items as well as following age or sex stratification. Association with frailty was also examined using an alternative instrument, weighted on s-IL-6R levels. Replication was attempted in UK Biobank dataset.

RESULTS

genetic predisposition to IL-6 signalling downregulation, weighted on CRP levels, was associated with lower risk of frailty, inserted either as categorical (odds ratio [95% confidence interval] = 0.15 [-3.39, -0.40], P = 0.013) or continuous variable (beta [se] = -0.09 [0.003], P = 0.0009). Sensitivity analyses revealed similar estimates across different MR methods with no evidence for horizontal pleiotropy or heterogeneity. Results remained robust after exclusion of depression or cognition-related FI items and following sex or age stratification. Genetically increased s-IL-6R levels were negatively correlated with frailty and this finding remained significant in a meta-analysis of UK Biobank and HELIAD cohorts.

CONCLUSION

our results support a potential causal effect of IL-6 signalling on frailty and further suggest that downregulation of IL-6 levels may reduce frailty risk.

Sex-Based Medicine Meets Psoriatic Arthritis: Lessons Learned and to Learn

Humorally associated autoimmune diseases generally show a female predominance whereas ankylosing spondylitis, a disease that overlaps with psoriatic arthritis (PsA), shows a male predominance. The present review ascertains the current knowledge of sex-specific differences related to psoriatic arthritis (PsA), a chronic, inflammatory condition associated with psoriasis. Sex differences may have important implications for clinical research in PsA and in terms of epidemiology (incidence, prevalence, lifetime risk, survival, and mortality), clinical, radiological, and laboratory features, and response to treatment. While nationwide surveys and large-scale databases and registries show no sex-specific differences, varying male/female ratios have been reported, ranging from 0.42 to 2.75 (comparable with those reported for psoriasis vulgaris: ranging from 0.28 to 2.38). This may reflect subtle, complex, nonlinear interactions between the biological make-up of the individual (genetic and epigenetic differences), hormonal components including menopausal status, environmental exposures including skeletal physical stressing, and psychological variables. There exists methodological heterogeneity and paucity of data concerning sex-specific differences, in terms of the specific population studied, study design, and the diagnostic criteria utilized. Harmonizing and reconciling these discrepancies would be of crucial importance in achieving the ambitious goals of personalized/individualized medicine and further standardized meta-data and Big Data could help disentangle and elucidate the precise mechanisms of underlying potential PsA sex-specific differences.