A Mendelian randomization study of IL6 signaling in cardiovascular diseases, immune-related disorders and longevity

Role of interleukin 6 signaling pathway in the anti-inflammatory effects of statins on coronary artery disease: Evidence from Mendelian randomization analysis

BACKGROUND

Statins are currently widely used in the prevention of coronary artery disease (CAD) primarily for lipid-lowering with a potential anti-inflammatory effect. However, it is not clear if their potential anti-inflammatory effects are mediated through the interleukin 6 (IL-6) signaling pathway.

METHODS

Using the Mendelian randomization (MR) approach followed by multivariable MR analyses, we examined the extent to which the effects of statins on CAD might be mediated through the IL-6 signaling pathway.

RESULTS

Our observations showed that HMG-CoA reductase, using LDL levels as a proxy, had a significant effect on upstream IL-6 (βMR = 0.47, P-IVW = 0.01) and nominally significant effects on IL-6RA (βMR = 0.22, P-IVW = 0.047) and APOB (βMR = 0.82, P-IVW = 1.8 × 10-33). While the IL-6 signaling cascade (IL-6RA βMR = -0.06, P-IVW = 3.45 × 10-20 and IL-6 βMR = -0.03, P-IVW = 0.09) and the anti-inflammatory effect of HMG-CoA reductase (βMR = -0.31, P-IVW = 0.01) was found to influence the risk of CAD, the multivariable MR (MVMR) model indicated that the anti-inflammatory effect of HMG-CoA reductase is not likely to be mediated through the IL-6 signaling cascade, including APOB and IL-6RA (MVMRβ = 0.23, P = 0.688).

CONCLUSIONS

Our findings suggest that statins may use inflammatory mechanisms independent of the IL-6 signaling pathway to prevent CAD. This result could potentially affect the definition of the target population for statin use.

Genetically predicted systemic inflammation and the risk of atrial fibrillation: A bidirectional two-sample Mendelian randomization study

Background

Systemic inflammation has been proposed to be associated with the incidence of atrial fibrillation (AF), but whether it is a cause or a consequence of AF remains uncertain. We sought to explore the causal associations between systemic inflammation and AF using bidirectional Mendelian randomization (MR) analysis.

Methods

Independent genetic variants strongly associated with AF were selected as instrumental variables from the largest genome-wide association study (GWAS) with up to 1,030,836 individuals. Regarding inflammation traits, genetic associations with 41 inflammatory cytokines and 5 inflammatory biomarkers were obtained from their corresponding GWASs databases. Effect estimates were primarily evaluated using the inverse-variance weighted (IVW) method, supplemented by sensitivity analyses using MR-Egger, weighted median, and MR-PRESSO methods.

Results

In our initial MR analyses, we observed suggestive associations of genetically predicted interleukin-17 (IL-17), interleukin-2 receptor subunit alpha (IL-2rα), and procalcitonin (PCT) with AF. One standard deviation (SD) increase in IL-17, IL-2rα, and PCT caused an increase in AF risk by 6.3 % (OR 1.063, 95 %CI 1.011---1.118, p = 0.018), 4.9 % (OR 1.049, 95 %CI 1.007---1.094, p = 0.023) and 3.4 % (OR 1.034, 95 %CI 1.005---1.064, p = 0.022), respectively. Furthermore, our reverse MR analyses indicated that genetically predicted AF contributed to a suggestive increase in the levels of macrophage inflammatory protein-1β (MIP1β) (β 0.055, 95 %CI 0.006 to 0.103, p = 0.028), while a decrease in the levels of fibrinogen (Fbg) (β -0.091, 95 %CI -0.140 to -0.041, p < 0.001), which remained significant after multiple test correction.

Conclusions

Our MR study identified several inflammatory biomarkers with suggestive causal associations regarding the upstream and downstream regulation of AF occurrence, offering new insights for therapeutic exploitation of AF. Further research is required to validate the underlying link between systemic inflammation and AF in larger cohorts.

IL-6 inhibition with clazakizumab in patients receiving maintenance dialysis: a randomized phase 2b trial

Inflammation mediated by interleukin-6 (IL-6) is strongly associated with cardiovascular risk. Here we evaluated clazakizumab, a monoclonal antibody targeting the IL-6 ligand, in a phase 2b dose-finding study. Adults with cardiovascular disease and/or diabetes receiving maintenance dialysis with high-sensitivity C-reactive protein (hs-CRP) ≥ 2 mg l-1 at baseline were randomized to receive clazakizumab (2.5 mg, 5 mg or 10 mg, n = 32 per dose group) or placebo (n = 31) every 4 weeks. The primary endpoint was the change from baseline in hs-CRP to week 12, expressed as the geometric mean ratio. Clazakizumab treatment signficantly reduced serum hs-CRP concentrations at week 12 by 86%, 90% and 92% relative to placebo in patients randomized to 2.5 mg, 5 mg or 10 mg clazakizumab, respectively (all P < 0.0001), meeting the primary outcome. With regard to secondary endpoints, clazakizumab treatment reduced serum fibrinogen, amyloid A, secretory phospholipase A2, and lipoprotein(a) concentrations, as well as increased mean serum albumin concentrations at 12 weeks, relative to placebo. The proportion of patients who achieved hs-CRP < 2.0 mg l-1 was 79%, 82% and 79% in the 2.5 mg, 5 mg and 10 mg clazakizumab groups, respectively, compared with 0% of placebo-treated patients. With regard to safety, no cases of sustained grade 3 or 4 thrombocytopenia or neutropenia were observed. Serious infections were seen with similar frequency in the placebo, clazakizumab 2.5 mg and clazakizumab 5 mg groups, but were numerically more frequent in the clazakizumab 10 mg group. The results of this trial indicate that in patients receiving maintenance dialysis, clazakizumab reduced inflammatory biomarkers associated with cardiovascular events. ClinicalTrials.gov registration: NCT05485961 .

Role of Inflammation in Depressive and Anxiety Disorders, Affect, and Cognition: Genetic and Non-Genetic Findings in the Lifelines Cohort Study

Background

Low-grade systemic inflammation is implicated in the pathogenesis of various neuropsychiatric conditions affecting mood and cognition. While much of the evidence concerns depression, large-scale population studies of anxiety, affect, and cognitive function are scarce. Importantly, causality remains unclear. We used complementary non-genetic, genetic risk score (GRS), and Mendelian randomization (MR) analyses to examine whether inflammatory markers are associated with affect, depressive and anxiety disorders, and cognitive performance in the Lifelines Cohort; and whether associations are likely to be causal.

Methods

Using data from up to 55,098 (59% female) individuals from the Dutch Lifelines cohort, we tested the cross-sectional and longitudinal associations of C-reactive protein (CRP) with (i) depressive and anxiety disorders; (ii) positive and negative affect scores, and (iii) five cognitive measures assessing attention, psychomotor speed, episodic memory, and executive functioning (figural fluency and working memory). Additionally, we examined the association between inflammatory marker GRSs (CRP, interleukin-6 [IL-6], IL-6 receptor [IL-6R and soluble IL-6R (sIL-6R)], glycoprotein acetyls [GlycA]) on these same outcomes (Nmax=57,946), followed by MR analysis examining evidence of causality of CRP on outcomes (Nmax=23,268). In genetic analyses, all GRSs and outcomes were z-transformed.

Results

In non-genetic analyses, higher CRP was associated with diagnosis of any depressive disorder, lower positive and higher negative affect scores, and worse performance on tests of figural fluency, attention, and psychomotor speed after adjusting for potential confounders, although the magnitude of these associations was small. In genetic analyses, CRPGRS was associated with any anxiety disorder (β=0.002, p=0.037, N=57,047) whereas GlycAGRS was associated with major depressive disorder (β=0.001, p=0.036; N=57,047). Both CRPGRS (β=0.006, p=0.035, N=57,946) and GlycAGRS (β=0.006, p=0.049; N=57,946) were associated with higher negative affect score. Inflammatory marker GRSs were not associated with cognitive performance, except sIL-6RGRS which was associated with poorer memory performance (β=-0.009, p=0.018, N=36,783). Further examination of the CRP-anxiety association using MR provided some weak evidence of causality (β=0.12; p=0.054).

Conclusions

Genetic and non-genetic analyses provide consistent evidence for an association between CRP and negative affect. Genetic analyses suggest that IL-6 signaling could be relevant for memory, and that the association between CRP and anxiety disorders could be causal. These results suggest that dysregulated immune physiology may impact a broad range of trans-diagnostic affective symptoms. However, given the small effect sizes and multiple tests conducted, future studies are required to investigate whether effects are moderated by sub-groups and whether these findings replicate in other cohorts.

Characterizing the polygenic overlap and shared loci between rheumatoid arthritis and cardiovascular diseases

BACKGROUND

Despite substantial research revealing that patients with rheumatoid arthritis (RA) have excessive morbidity and mortality of cardiovascular disease (CVD), the mechanism underlying this association has not been fully known. This study aims to systematically investigate the phenotypic and genetic correlation between RA and CVD.

METHODS

Based on UK Biobank, we conducted two cohort studies to evaluate the phenotypic relationships between RA and CVD, including atrial fibrillation (AF), coronary artery disease (CAD), heart failure (HF), and stroke. Next, we used linkage disequilibrium score regression, Local Analysis of [co]Variant Association, and bivariate causal mixture model (MiXeR) methods to examine the genetic correlation and polygenic overlap between RA and CVD, using genome-wide association summary statistics. Furthermore, we explored specific shared genetic loci by conjunctional false discovery rate analysis and association analysis based on subsets.

RESULTS

Compared with the general population, RA patients showed a higher incidence of CVD (hazard ratio [HR] = 1.21, 95% confidence interval [CI]: 1.15-1.28). We observed positive genetic correlations of RA with AF and stroke, and a mixture of negative and positive local genetic correlations underlying the global genetic correlation for CAD and HF, with 13 ~ 33% of shared genetic variants for these trait pairs. We further identified 23 pleiotropic loci associated with RA and at least one CVD, including one novel locus (rs7098414, TSPAN14, 10q23.1). Genes mapped to these shared loci were enriched in immune and inflammatory-related pathways, and modifiable risk factors, such as high diastolic blood pressure.

CONCLUSIONS

This study revealed the shared genetic architecture of RA and CVD, which may facilitate drug target identification and improved clinical management.

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.

Genetic Factors Altering Immune Responses in Atrial Fibrillation: JACC Review Topic of the Week

Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide and is associated with a range of adverse clinical outcomes. Accumulating evidence points to inflammatory processes resulting from innate immune responses as a cornerstone in AF pathogenesis. Genetic and epigenetic factors affecting leukocytes have been identified as key modulators of the inflammatory response. Inherited variants in genes encoding proteins involved in the innate immune response have been associated with increased risk for AF recurrence and stroke in AF patients. Furthermore, acquired somatic mutations associated with clonal hematopoiesis of indeterminate potential, leukocyte telomere shortening, and epigenetic age acceleration contribute to increased AF risk. In individuals carrying clonal hematopoiesis of indeterminate potential, myocardial monocyte-derived macrophage shift toward a proinflammatory phenotype may precipitate AF. Further studies are needed to better understand the role of genetic regulation of the native immune response in atrial arrhythmogenesis and its therapeutic potential as a target for personalized medicine.

Inflammatory cytokines and oral lichen planus: a Mendelian randomization study

Background

Inflammatory cytokines have long been considered closely related to the development of oral lichen planus (OLP), and we further explored the causal relationship between the two by Mendelian randomization (MR) method.

Methods

We performed bidirectional MR analyses by large genome-wide association studies (GWAS). The data included a large-scale OLP dataset, as well as datasets of 41 inflammatory cytokines. All data were obtained from the University of Bristol database, which includes 41 inflammatory cytokines, and the GWAS Catalog database, which includes 91 inflammatory cytokines. OLP data were obtained from the Finngen database, which includes 6411 cases and 405770 healthy controls. We used the inverse variance weighted (IVW) method, MR-Egger method, weighted median method, simple mode method and weighted mode method to analyze the causal relationship between inflammatory cytokines and OLP, and we also combined with sensitivity analysis to further verify the robustness of the results. We performed a meta-analysis of positive or potentially positive results for the same genes to confirm the reliability of the final results.

Results

We primarily used the IVW analysis method, corrected using the Benjamin Hochberg (BH) method. When p<0.00038 (0.05/132), the results are significantly causal; when 0.00038

Conclusion

There is a causal association between OLP and some inflammatory cytokines, which may play an important role in the pathogenesis of OLP and require further attention.

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Key Words

• Mendelian randomization
• immunity
• inflammation
• inflammatory cytokines
• oral lichen planus

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MESH Headings

• Humans
• Cytokines/genetics
• Genome-Wide Association Study
• Lichen Planus, Oral/genetics
• Mendelian Randomization Analysis
• Reproducibility of Results

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Affiliation(s)

Xin Chen Department of Oral and Maxillofacial Surgery, Jiangyin People's Hospital Affiliated to Nantong University, Wuxi, Jiangsu, China
Simin Zhang Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, China Department of General Dentistry, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, China
Xiao Wu Endodontic Department, School of Stomatology, Nanjing Medical University, Nanjing, Jiangsu, China
Yuxi Lei Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, China Department of Emergency Room, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, China
Bing Lei Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, China Department of General Dentistry, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, China
Zhibai Zhao Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, China Department of General Dentistry, College of Stomatology, Xi’an Jiaotong University, Xi’an, Shaanxi, China

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The Impact of Different Intensities of Physical Activity on Serum Urate and Gout: A Mendelian Randomization Study

Physical activity is a potential protective factor against gout, but the role of exercise intensity in this context remains unclear. To overcome the limitations of observational studies in causal inference, this study employed a two-sample Mendelian randomization approach to explore the impact of different genetically proxied/predicted intensities of physical activity on serum urate concentration and the incidence of gout. Our data related to physical activity, serum urate, and gout were obtained from the UK Biobank, the Global Urate Genetics Consortium (GUGC), and the FinnGen dataset, respectively. Walking was included as representative of typical low-intensity physical activity in the analysis, and the other two types were moderate and vigorous physical activities. The estimation methods we used included the inverse-variance-weighted (IVW) method, MR-Egger regression, weighted-median method, simple-mode method, and weighted-mode method. Sensitivity analyses involved Rucker's framework, Cochran's Q test, funnel plots, MR-PRESSO outlier correction, and leave-one-out analysis. We found suggestive evidence from the inverse-variance-weighted method that moderate physical activity was a potential factor in reducing the incidence of gout (OR = 0.628, p = 0.034), and this association became more substantial in our subsequent sensitivity analysis (OR = 0.555, p = 0.006). However, we observed no distinctive effects of physical activity on serum urate concentration. In conclusion, our study supports some findings from observational studies and emphasizes the preventive role of moderate physical activity against gout. Given the limitations of the existing datasets, we call for future reexamination and expansion of our findings using new GWAS data.

Exploring the causal association of rheumatoid arthritis with atrial fibrillation: a Mendelian randomization study

BACKGROUND

It has been proved that rheumatoid arthritis (RA) patients have high incidence of atrial fibrillation (AF). Nevertheless, whether they have causal relevance is uncertain. This study aimed to explore and verify the authenticity of causal relationship between RA and AF using Mendelian randomization (MR).

METHODS

The genome-wide association study (GWAS) summary data from Biobank Japan Project (BBJ) (RA, 4199 cases and 208,254 controls) were regarded as exposure data and the GWAS data from European Bio-informatics Institute database (EBI) (AF, 15,979 cases and 102,776 controls) as outcome data. The causal effect was appraised by the inverse variance weighted (IVW) method, MR-Egger regression, and weighted median estimator. MR-robust adjusted profile score (MR-RAPS) method was delivered to examine the robustness of causal relationship and MR Pleiotropy Residual Sum and Outlier (MR-PRESSO) method to control horizontal (directional) pleiotropy.

RESULTS

The results indicated that RA increased the risk of AF (IVW, the odds ratio (OR) = 1.060; 95% confidence interval (CI), 1.028 to 1.092; p = 1.411 × 10-4; weighted median, OR = 1.046, 95% CI, 1.002 to 1.093, p = 0.047). The MR analysis also showed this causal effect through all four IVW methods with various statistical algorithms. Both MR-RAPS and MR-PRESSO supported the causality of RA and AF. Also, the MR-PRESSO result indicated the absence of apparent pleiotropy.

CONCLUSION

There is a causal association between RA and AF. RA patients are genetically more vulnerable to AF. This study may contribute to further exploring early clinical prevention and fundamental mechanism of AF in patients with RA. Key Points • We provided some genetic evidence for the causal link between rheumatoid arthritis (RA) and atrial fibrillation (AF) with multiple Mendelian randomization (MR) methods. • RA patients were genetically more vulnerable to AF. • This study partly shed light on latent fundamental mechanisms underlying RA-induced AF and inspired future studies on RA-AF relationship.

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.

Therapeutic Potential of Downregulated Interleukin-6 Signaling for the Treatment of Chronic Pain: A Mendelian Randomization Study

Introduction

While numerous studies have emphasized the pivotal involvement of the Interleukin 6 (IL-6) pathway in the development of chronic pain, the causal nature of this relationship remains uncertain.

Methods

In this study, we opted to include genetic variants situated within the locus of the IL-6 receptor (IL-6R) that exhibited associations with C-reactive protein (CRP) levels. CRP serves as a downstream effector in the IL-6 pathway. Utilizing these variants as genetic proxies, we aimed to modulate IL-6 signaling. Employing a two-sample Mendelian randomization (MR) approach, we investigated the potential link between the genetic proxy and seven distinct subtypes of chronic pain, categorized based on their corresponding body locations. Moreover, we examined the relationship between chronic pain and an alternative instrument of IL-6 signaling that was weighted based on s-IL-6R levels. Furthermore, we conducted exploratory analyses to estimate the plausible causal association between CRP, gp130, and the subtypes of chronic pain.

Results

Our analysis showed that genetic proxied downregulation of IL-6 signaling, weighted on CRP levels, was linked to a reduced risk of chronic back and knee pain. The sensitivity analyses across various MR methods confirmed the consistency of the findings and showed no evidence of horizontal pleiotropy or heterogeneity. Moreover, the results remained robust with different sets of instrument variables. A genetically increased level of s-IL-6R was also negatively associated with chronic back and knee pain. However, there was no causal relationship between CRP and gp130 with chronic pain.

Conclusion

Based on our findings, there is evidence to suggest a potential causal relationship between IL-6 signaling and chronic back and knee pain. Consequently, the downregulation of IL-6 signaling holds promise as a potential therapeutic target for addressing chronic back and knee pain.

Mediation effect of stroke recurrence in the association between post-stroke interleukin-6 and functional disability

AIM

Post-stroke inflammation increases the risk of functional disability through enlarged cerebral infarct size directly and follow-up stroke event indirectly. We aimed to use post-stroke proinflammatory cytokine interleukin-6 (IL-6) as a marker of inflammatory burden and quantify post-stroke inflammation's direct and indirect effect on functional disability.

METHODS

We analyzed patients with acute ischemic stroke admitted to 169 hospitals in the Third China National Stroke Registry. Blood samples were collected within 24 h of admission. Stroke recurrence and functional outcome measured by the modified Rankin scale (mRS) were assessed via face-to-face interviews at 3 months. Functional disability was defined as an mRS score ≥2. Mediation analyses under the counterfactual framework were performed to examine the potential causal chain in which stroke recurrence may mediate the relationship between IL-6 and functional outcome.

RESULTS

Among the 7053 analyzed patients, the median (interquartile range [IQR]) NIHSS score was 3 (1-5), and the median (IQR) level of IL-6 was 2.61 (1.60-4.73) pg/mL. Stroke recurrence was observed in 458 (6.5%) patients, and functional disability was seen in 1708 (24.2%) patients at the 90-day follow-up. Per stand deviation (4.26 pg/mL) increase in the concentration of IL-6 was associated with an increased risk of stroke recurrence (adjusted odds ratio [aOR], 1.19; 95% CI, 1.09-1.29) and disability (aOR, 1.22; 95% CI, 1.15-1.30) within 90 days. Mediation analyses revealed that 18.72% (95% CI, 9.26%-28.18%) of the relationship between IL-6 and functional disability was mediated by stroke recurrence.

CONCLUSIONS

Stroke recurrence mediates less than 20% of the association between IL-6 and functional outcome at 90 days among patients with acute ischemic stroke. In addition to typical secondary prevention strategies for preventing stroke recurrence, more attention should be paid to novel anti-inflammatory therapy to improve functional outcomes directly.

Appraising the Causal Role of Risk Factors in Coronary Artery Disease and Stroke: A Systematic Review of Mendelian Randomization Studies

BACKGROUND Mendelian randomization (MR) offers a powerful approach to study potential causal associations between exposures and health outcomes by using genetic variants associated with an exposure as instrumental variables. In this systematic review, we aimed to summarize previous MR studies and to evaluate the evidence for causality for a broad range of exposures in relation to coronary artery disease and stroke. METHODS AND RESULTS MR studies investigating the association of any genetically predicted exposure with coronary artery disease or stroke were identified. Studies were classified into 4 categories built on the significance of the main MR analysis results and its concordance with sensitivity analyses, namely, robust, probable, suggestive, and insufficient. Studies reporting associations that did not perform any sensitivity analysis were classified as nonevaluable. We identified 2725 associations eligible for evaluation, examining 535 distinct exposures. Of them, 141 were classified as robust, 353 as probable, 110 as suggestive, and 926 had insufficient evidence. The most robust associations were observed for anthropometric traits, lipids, and lipoproteins and type 2 diabetes with coronary artery; disease and clinical measurements with coronary artery disease and stroke; and thrombotic factors with stroke. CONCLUSIONS Despite the large number of studies that have been conducted, only a limited number of associations were supported by robust evidence. Approximately half of the studies reporting associations presented an MR sensitivity analysis along with the main analysis that further supported the causality of associations. Future research should focus on more thorough assessments of sensitivity MR analyses and further assessments of mediation effects or nonlinearity of associations.

Biomarker, Imaging, and Clinical Factors Associated With Overt and Covert Stroke in Patients With Atrial Fibrillation

BACKGROUND

Atrial fibrillation is a major risk factor for stroke and silent brain infarcts. We studied whether a multimodal approach offers additional insights to the CHA2DS2-VASc score in predicting stroke or new brain infarcts on magnetic resonance imaging (MRI) over a 2-year follow-up.

METHODS

Swiss-AF is a prospective, multicenter cohort study of patients with known atrial fibrillation. We included patients with available brain MRI both at enrollment and 2 years later. The dates of the baseline and follow-up visits ranged from March 2014 to November 2020. The primary outcome was assessed 2 years after baseline and was defined as a composite of clinically identified stroke or any new brain infarct on the 2-year MRI. We compared a multivariable logistic regression model including prespecified clinical, biomarker, and baseline MRI variables to the CHA2DS2-VASc score.

RESULTS

We included 1232 patients, 89.8% of them taking oral anticoagulants. The primary outcome occurred in 78 patients (6.3%). The following baseline variables were included in the final multivariate model and were significantly associated with the primary outcome: white matter lesion volume in milliliters (adjusted odds ratio [aOR], 1.91 [95% CI, 1.45-2.56]), NT-proBNP (N-terminal pro-B-type natriuretic peptide; aOR, 1.75 [95% CI, 1.20-2.63]), GDF-15 (growth differentiation factor-15; aOR, 1.68 [95% CI, 1.11-2.53]), serum creatinine (aOR, 1.50 [95% CI, 1.02-2.22]), IL (interleukin)-6 (aOR, 1.37 [95% CI, 1.00-1.86]), and hFABP (heart-type fatty acid-binding protein; aOR, 0.48 [95% CI, 0.31-0.73]). Overall performance and discrimination of the new model was superior to that of the CHA2DS2-VASc score (C statistic, 0.82 [95% CI, 0.77-0.87] versus 0.64 [95% CI, 0.58-0.70]).

CONCLUSIONS

In patients with atrial fibrillation, a model incorporating white matter lesion volume on baseline MRI and selected blood markers yielded new insights on residual stroke risk despite a high proportion of patients on oral anticoagulants. This may be relevant to develop further preventive measures.

Genetics of circulating inflammatory proteins identifies drivers of immune-mediated disease risk and therapeutic targets

Circulating proteins have important functions in inflammation and a broad range of diseases. To identify genetic influences on inflammation-related proteins, we conducted a genome-wide protein quantitative trait locus (pQTL) study of 91 plasma proteins measured using the Olink Target platform in 14,824 participants. We identified 180 pQTLs (59 cis, 121 trans). Integration of pQTL data with eQTL and disease genome-wide association studies provided insight into pathogenesis, implicating lymphotoxin-α in multiple sclerosis. Using Mendelian randomization (MR) to assess causality in disease etiology, we identified both shared and distinct effects of specific proteins across immune-mediated diseases, including directionally discordant effects of CD40 on risk of rheumatoid arthritis versus multiple sclerosis and inflammatory bowel disease. MR implicated CXCL5 in the etiology of ulcerative colitis (UC) and we show elevated gut CXCL5 transcript expression in patients with UC. These results identify targets of existing drugs and provide a powerful resource to facilitate future drug target prioritization.

Proteome-Wide Mendelian Randomization Analysis Identified Potential Drug Targets for Atrial Fibrillation

Background Finding effective and safe therapeutic drugs for atrial fibrillation (AF) is an important concern for clinicians. Proteome-wide Mendelian randomization analysis provides new ideas for finding potential drug targets. Methods and Results Using a proteome-wide Mendelian randomization approach, we assessed the genetic predictive causality between thousands of proteins and AF risk and found that genetically predicted plasma levels of phosphomevalonate kinase, tumor necrosis factor ligand superfamily member 12, sulfhydryl oxidase 2, interleukin-6 receptor subunit alpha, and low-affinity immunoglobulin gamma Fc region receptor II-b might decrease AF risk, while genetically predicted plasma levels of beta-mannosidase, collagen alpha-1(XV) chain, ANXA4 (annexin A4), COF2 (cofilin-2), and RAB1A (Ras-related protein Rab-1A) might increase AF risk (P<3.4×10-5). By using different Mendelian randomization methods and instrumental variable selection thresholds, we performed sensitivity analyses in 30 scenarios to test the robustness of positive findings. Replication analyses were also performed in independent samples to further avoid false-positive findings. Drugs targeting tumor necrosis factor ligand superfamily member 12, interleukin-6 receptor subunit alpha, low-affinity immunoglobulin gamma Fc region receptor II-b, and annexin A4 are approved or in development. The results of the phenome-wide Mendelian randomization analysis showed that changing the plasma levels of phosphomevalonate kinase, cofilin-2, annexin A4, Ras-related protein Rab-1A, sulfhydryl oxidase 2, and collagen alpha-1(XV) chain did not increase the risk of other diseases while decreasing the risk of AF. Conclusions We found a significant causal association between genetically predicted levels of 10 plasma proteins and AF risk. Four of these proteins have drugs targeting them that are approved or in development, and our results suggest the potential for these drugs to treat AF or cause AF. Sulfhydryl oxidase 2, low-affinity immunoglobulin gamma Fc region receptor II-b, and beta-mannosidase have not been suggested by previous laboratory or epidemiological studies to be associated with AF and may reveal new pathophysiological pathways as well as therapeutic targets for AF.

Unravelling the genetic causality of immunoglobulin G N-glycans in ischemic stroke

BACKGROUND

Evidence suggests that immunoglobulin G (IgG) N-glycosylation is associated with ischemic stroke (IS). However, the causality of IgG N-glycosylation for IS remains unknown.

METHODS

Two-sample Mendelian randomization (MR) analyses were performed to investigate the potential causal effects of genetically determined IgG N-glycans on IS using publicly available summarized genetic data from East Asian and European populations. Genetic instruments were used as proxies for IgG N-glycan traits. IgG N-glycans were analysed using ultra-performance liquid chromatography. Four complementary MR methods were performed, including the inverse variance weighted method (IVW), MR‒Egger, weighted median and penalized weighted median. Furthermore, to further test the robustness of the results, MR based on Bayesian model averaging (MR-BMA) was then applied to select and prioritize IgG N-glycan traits as risk factors for IS.

RESULTS

After correcting for multiple testing, in two-sample MR analyses, genetically predicted IgG N-glycans were unrelated to IS in both East Asian and European populations, and the results remained consistent and robust in the sensitivity analysis. Moreover, MR-BMA also showed consistent results in both East Asian and European populations.

CONCLUSIONS

Contrary to observational studies, the study did not provide enough genetic evidence to support the causal associations of genetically predicted IgG N-glycan traits and IS, suggesting that N-glycosylation of IgG might not directly involve in the pathogenesis of IS.

Association between inflammation and cognition: Triangulation of evidence using a population-based cohort and Mendelian randomization analyses

BACKGROUND

Inflammation is associated with cognitive functioning and dementia in older adults, but whether inflammation is related to cognitive functioning in youth and whether these associations are causal remains unclear.

METHODS

In a population-based cohort (Avon Longitudinal Study of Parents and Children; ALSPAC), we investigated cross-sectional associations of inflammatory markers (C-reactive protein [CRP], Interleukin-6 [IL-6] and Glycoprotein acetyls [GlycA]) with measures of cold (working memory, response inhibition) and hot (emotion recognition) cognition at age 24 (N = 3,305 in multiple imputation models). Furthermore, we conducted one-sample and two-sample bidirectional Mendelian randomization (MR) analyses to examine potential causal effects of genetically-proxied inflammatory markers (CRP, GlycA, IL-6, IL-6 receptor, soluble IL-6 receptor) on cognitive measures (above) and on general cognitive ability.

RESULTS

In the ALSPAC cohort, there was limited evidence of an association between standardised inflammatory markers and standardised cognitive measures at age 24 after adjusting for potential confounders (N = 3,305; beta range, -0.02 [95 % confidence interval (CI) -0.06 to 0.02, p = 0.27] to 0.02 [95 % CI -0.02 to 0.05, p = 0.33]). Similarly, we found limited evidence of potential effects of 1-unit increase in genetically-proxied inflammatory markers on standardised working memory, emotion recognition or response inhibition in one-sample MR using ALSPAC data (beta range, -0.73 [95 % CI -2.47 to 1.01, p = 0.41] to 0.21 [95 % CI -1.42 to 1.84, p = 0.80]; or on standardised general cognitive ability in two-sample MR using the latest Genome-Wide Association Study (GWAS) datasets (inverse-variance weighted beta range, -0.02 [95 % CI -0.05 to 0.01, p = 0.12] to 0.03 [95 % CI -0.01 to 0.07, p = 0.19]).

CONCLUSIONS

Our MR findings do not provide strong evidence of a potential causal effect of inflammatory markers (CRP, IL-6, IL-6 receptor, GlycA) on the cognitive functions examined here. Given the large confidence intervals in the one-sample MR, larger GWAS of specific cognitive measures are needed to enable well-powered MR analyses to investigate whether inflammation causally influences specific cognitive domains.

Evaluation of the association between circulating IL-1β and other inflammatory cytokines and incident atrial fibrillation in a cohort of postmenopausal women

BACKGROUND

Inflammatory cytokines play a role in atrial fibrillation (AF). Interleukin (IL)-1β, which is targeted in the treatment of ischemic heart disease, has not been well-studied in relation to AF.

METHODS

Postmenopausal women from the Women's Health Initiative were included. Cox proportional hazards regression models were used to evaluate the association between log-transformed baseline cytokine levels and future AF incidence. Models were adjusted for body mass index, age, race, education, hypertension, diabetes, hyperlipidemia, current smoking, and history of coronary heart disease, congestive heart failure, or peripheral artery disease.

RESULTS

Of 16,729 women, 3,943 developed AF over an average of 8.5 years. Racial and ethnic groups included White (77.4%), Black/African-American (16.1%), Asian (2.7%), American Indian/Alaska Native (1.0%), and Hispanic (5.5%). Baseline IL-1β log continuous levels were not significantly associated with incident AF (HR 0.86 per 1 log [pg/mL] increase, P= .24), similar to those of other inflammatory cytokines, IL-7, IL-8, IL-10, IGF-1, and TNF-α. There were significant associations between C-reactive protein (CRP) and IL-6 with incident AF.

CONCLUSIONS

In this large cohort of postmenopausal women, there was no significant association between IL-1β and incident AF, although downstream effectors, CRP and IL-6, were associated with incident AF.

Mendelian randomization as a tool to inform drug development using human genetics

Drug development is essential to the advancement of human health, however, the process is slow, costly, and at high risk of failure at all stages. A promising strategy for expediting and improving the probability of success in the drug development process is the use of naturally randomized human genetic variation for drug target identification and validation. These data can be harnessed using the Mendelian randomization (MR) analytic paradigm to proxy the lifelong consequences of genetic perturbations of drug targets. In this review, we discuss the myriad applications of the MR paradigm for human drug target identification and validation. We review the methodology and applications of MR, key limitations of MR, and potential future opportunities for research. Throughout the review, we refer to illustrative examples of MR analyses investigating the consequences of genetic inhibition of interleukin 6 signaling which, in some cases, have anticipated results from randomized controlled trials. As human genetic data become more widely available, we predict that MR will serve as a key pillar of support for drug development efforts.

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.

Proteomics Analysis of Genetic Liability of Abdominal Aortic Aneurysm Identifies Plasma Neogenin and Kit Ligand: The ARIC Study

BACKGROUND

Genome-wide association studies have reported 23 gene loci related to abdominal aortic aneurysm (AAA)-a potentially lethal condition characterized by a weakened dilated vessel wall. This study aimed to identify proteomic signatures and pathways related to these risk loci to better characterize AAA genetic susceptibility.

METHODS

Plasma concentrations of 4870 proteins were determined using a DNA aptamer-based array. Linear regression analysis estimated the associations between the 23 risk alleles and plasma protein levels with adjustments for potential confounders in a race-stratified analysis of 1671 Black and 7241 White participants. Significant proteins were then evaluated for their prediction of clinical AAA (454 AAA events in 11 064 individuals), and those significantly associated with AAA were further interrogated using Mendelian randomization analysis.

RESULTS

Risk variants proximal to PSRC1-CELSR2-SORT1, PCIF1-ZNF335-MMP9, RP11-136O12.2/TRIB1, ZNF259/APOA5, IL6R, PCSK9, LPA, and APOE were associated with 118 plasma proteins in Whites and 59 were replicated in Black participants. Novel associations with clinical AAA incidence were observed for kit ligand (HR, 0.59 [95% CI, 0.42-0.82] for top versus first quintiles) and neogenin (HR, 0.64 [95% CI, 0.46-0.88]) over a median 21.2-year follow-up; neogenin was also associated with ultrasound-detected asymptomatic AAA (N=4295; 57 asymptomatic AAA cases). Mendelian randomization inverse variance weighted estimates suggested that AAA risk is promoted by lower levels of kit ligand (OR per SD=0.67; P=1.4×10-5) and neogenin (OR per SD=0.50; P=0.03).

CONCLUSIONS

Low levels of neogenin and kit ligand may be novel risk factors for AAA development in potentially causal pathways. These findings provide insights and potential targets to reduce AAA susceptibility.

Can Intelligence Affect Alcohol-, Smoking-, and Physical Activity-Related Behaviors? A Mendelian Randomization Study

People with high levels of intelligence are more aware of risk factors, therefore choosing a healthier lifestyle. This assumption seems reasonable, but is it true? Previous studies appear to agree and disagree. To cope with the uncertainty, we designed a mendelian randomization (MR) study to examine the causal effects of genetically proxied intelligence on alcohol-, smoking-, and physical activity (PA)-related behaviors. We obtained genome-wide association study (GWAS) datasets concerning these variables from separate studies or biobanks and used inverse-variance weighted (IVW) or MR-Egger estimator to evaluate the causal effects according to an MR protocol. The MR-Egger intercept test, MR-PRESSO, and funnel plots were employed for horizontal pleiotropy diagnosis. The Steiger test (with reliability test), Cochran's Q test, MR-PRESSO, and leave-one-out method were employed for sensitivity analysis. We found significant or potential effects of intelligence on alcohol dependence (OR = 0.749, p = 0.003), mental and behavioral disorders due to alcohol (OR = 0.814, p = 0.009), smoking (OR = 0.585, p = 0.005), and smoking cessation (OR = 1.334, p = 0.001). Meanwhile, we found significant or potential effects on walking duration (B = -0.066, p < 0.001), walking frequency (B = -0.055, p = 0.031), moderate PA frequency (B = -0.131, p < 0.001), and vigorous PA frequency (B = -0.070, p = 0.001), but all in a negative direction. In conclusion, our findings reinforce some existing knowledge, indicate the complexity of the health impacts of human intelligence, and underline the value of smoking and alcohol prevention in less intelligent populations. Given the existing limitations in this study, particularly the potential reverse causality in some estimations, re-examinations are warranted in future research.

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.

Inflammatory markers and the risk of idiopathic sudden sensorineural hearing loss: A Mendelian randomization study

Background

Observational studies suggest that inflammatory markers may increase the risk of idiopathic sudden sensorineural hearing loss (ISSHL). However, the causal relationship between the two has not been established. We sought to assess the possible causal effect between several genetically predicted inflammatory markers and ISSHL by Mendelian random (MR) analysis.

Methods

We extracted single nucleotide polymorphisms (SNPs) associated with C-reactive protein (CRP), Tumor necrosis factor-α (TNF-α), and fibrinogen from abstract data from the European Individual Large genome-wide association studies (GWAS). Genetic data for ISSHL were obtained from the FinnGen study (n = 196,592). Effect estimates were assessed using inverse variance weighting (IVW) as the primary method. Sensitivity analyses were performed using weighted median, MR-Egger, and MR-PRESSO to evaluate heterogeneity and pleiotropy.

Results

In the random-effects IVW approach, there was a significant causal relationship between genetic susceptibility to CRP levels and ISSHL (OR = 1.23, 95% CI = 1.02-1.49, P = 0.03). In contrast, genetic TNF-α and fibrinogen were not risked factors for ISSHL (OR = 1.14, 95% CI = 0.88-1.49, P = 0.30; OR = 0.74, 95% CI = 0.07-7.96, P = 0.30; OR = 1.05, 95% CI = 0.88-1.25, P = 0.59). All the above results were consistent after validation by different Mendelian randomization methods and sensitivity analyses.

Conclusion

This Mendelian randomization study provides causal evidence that CRP is a risk factor for ISSHL, while TNF-α and fibrinogen do not increase the risk for ISSHL Introduction.

Causal risk factors for asthma in Mendelian randomization studies: A systematic review and meta-analysis

BACKGROUND

Several risk factors for asthma have been proposed; however, the causality of these associations is sometimes unclear. Mendelian randomization is a powerful epidemiological approach that can help elucidate the causality of risk factors. The aim of the present study was to identify causal risk factors for asthma through Mendelian Randomization studies.

METHODS

A systematic search of PubMed and EMBASE was conducted, to identify studies investigating risk factors for asthma or respiratory allergies through Mendelian Randomization. When two or more studies investigated the same risk factor a meta-analysis was conducted. Of 239 studies initially identified, 41 were included.

RESULTS

A causal association between adiposity and adult asthma risk was found in 10 out of 12 studies with a summary risk ratio of 1.05 per kg/m² increase in BMI (95% CI: 1.03-1.07). Puberty timing (n = 3), alcohol (n = 2), and linoleic acid (n = 1) had causal effects on asthma risk, while vitamins/minerals (n = 6) showed no consistent effect on asthma. The effect of smoking on adult asthma conflicted between studies. Several of the significant associations of asthma with immune related proteins (n = 5) and depression (n = 2) investigated through multiple traits analyses could generally benefit from replications in independent datasets.

CONCLUSION

This systematic review and meta-analysis found evidence for causal effects of adiposity, puberty timing, linoleic acid, alcohol, immune related proteins, and depression on risk of asthma.

Genome-Wide Integration of Genetic and Genomic Studies of Atopic Dermatitis: Insights into Genetic Architecture and Pathogenesis

Atopic dermatitis (AD) is a common heterogeneous, chronic, itching, and inflammatory skin disease. Genetic studies have identified multiple AD susceptibility genes. However, the genetic architecture of AD has not been elucidated. In this study, we conducted a large-scale meta-analysis of AD (35,647 cases and 1,013,885 controls) to characterize the genetic basis of AD. The heritability of AD in different datasets varied from 0.6 to 7.1%. We identified 31 previously unreported genes by integrating multiomics data. Among the 31 genes, MCL1 was identified as a potential treatment target for AD by mediating gene‒drug interactions. Tissue enrichment analyses and phenome-wide association study provided strong support for the role of the hemic and immune systems in AD. Across 1,207 complex traits and diseases, genetic correlations indicated that AD shared links with multiple respiratory phenotypes. The phenome-wide Mendelian randomization analysis (Mendelian randomization‒phenome-wide association study) revealed that the age of onset of diabetes exhibited a positive causal effect on AD (inverse-variance weighted β = 0.39, SEM = 0.09, P = 2.77 × 10^-5). Overall, these results provide important insights into the genetic architecture of AD and will lead to a more thorough and complete understanding of the molecular mechanisms underlying AD.

Obesity-related biomarkers underlie a shared genetic architecture between childhood body mass index and childhood asthma

Obesity and asthma are both common diseases with high population burden worldwide. Recent genetic association studies have shown that obesity is associated with asthma in adults. The relationship between childhood obesity and childhood asthma, and the underlying mechanisms linking obesity to asthma remain to be clarified. In the present study, leveraging large-scale genetic data from UK biobank and several other data sources, we investigated the shared genetic components between body mass index (BMI, n = 39620) in children and childhood asthma (n_case = 10524, n_control = 373393). We included GWAS summary statistics for nine obesity-related biomarkers to evaluate potential biological mediators underlying obesity and asthma. We found a genetic correlation (Rg = 0.10, P = 0.02) between childhood BMI and childhood asthma, whereas the genetic correlation between adult BMI (n = 371541) and childhood asthma was null (Rg = -0.03, P = 0.21). Genomic structural equation modeling analysis further provided evidence that the genetic effect of childhood BMI on childhood asthma (standardized effect size 0.17, P = 0.009) was not driven by the genetic component of adult BMI. Bayesian colocalization analysis identified a shared causal variant rs12436181 that was mapped to gene AMN using gene expression data in lung tissue. Mendelian randomization showed that the odds ratio of childhood asthma for one standard deviation higher of childhood BMI was 1.13 (95% confidence interval: 0.96-1.34). A systematic survey of obesity-related biomarkers showed that IL-6 and adiponectin are potential biological mediators linking obesity and asthma in children. This large-scale genetic study provides evidence that unique childhood obesity pathways could lead to childhood asthma. The findings shed light on childhood asthma pathogenic mechanisms and prevention.

The dynamic changes and sex differences of 147 immune-related proteins during acute COVID-19 in 580 individuals

INTRODUCTION

Severe COVID-19 leads to important changes in circulating immune-related proteins. To date it has been difficult to understand their temporal relationship and identify cytokines that are drivers of severe COVID-19 outcomes and underlie differences in outcomes between sexes. Here, we measured 147 immune-related proteins during acute COVID-19 to investigate these questions.

METHODS

We measured circulating protein abundances using the SOMAscan nucleic acid aptamer panel in two large independent hospital-based COVID-19 cohorts in Canada and the United States. We fit generalized additive models with cubic splines from the start of symptom onset to identify protein levels over the first 14 days of infection which were different between severe cases and controls, adjusting for age and sex. Severe cases were defined as individuals with COVID-19 requiring invasive or non-invasive mechanical respiratory support.

RESULTS

580 individuals were included in the analysis. Mean subject age was 64.3 (sd 18.1), and 47% were male. Of the 147 proteins, 69 showed a significant difference between cases and controls (p < 3.4 × 10-4). Three clusters were formed by 108 highly correlated proteins that replicated in both cohorts, making it difficult to determine which proteins have a true causal effect on severe COVID-19. Six proteins showed sex differences in levels over time, of which 3 were also associated with severe COVID-19: CCL26, IL1RL2, and IL3RA, providing insights to better understand the marked differences in outcomes by sex.

CONCLUSIONS

Severe COVID-19 is associated with large changes in 69 immune-related proteins. Further, five proteins were associated with sex differences in outcomes. These results provide direct insights into immune-related proteins that are strongly influenced by severe COVID-19 infection.

Independent effects of adiposity measures on risk of atrial fibrillation in men and women: a study of 0.5 million individuals

BACKGROUND

Atrial fibrillation (AF) has a higher prevalence in men than in women and is associated with measures of adiposity and lean mass (LM). However, it remains uncertain whether the risks of AF associated with these measures vary by sex.

METHODS

Among 477 904 UK Biobank participants aged 40-69 without prior AF, 23 134 incident AF cases were identified (14 400 men, 8734 women; median follow-up 11.1 years). Cox proportional hazards models were used to estimate the covariate adjusted hazard ratios (HRs) describing the association of AF with weight, measures of adiposity [fat mass (FM), waist circumference (WC)] and LM, and their independent relevance, by sex.

RESULTS

Weight and WC were independently associated with risk of AF [HR: 1.25 (1.23-1.27) per 10 kg, HR: 1.11 (1.09-1.14) per 10 cm, respectively], with comparable effects in both sexes. The association with weight was principally driven by LM, which, per 5 kg, conferred double the risk of AF compared with FM when mutually adjusted [HR: 1.20 (1.19-1.21), HR: 1.10 (1.09-1.11), respectively]; however, the effect of LM was weaker in men than in women (p-interaction = 4.3 x 10-9). Comparing the relative effects of LM, FM and WC identified different patterns within each sex; LM was the strongest predictor for both, whereas WC was stronger than FM in men but not in women.

CONCLUSIONS

LM and FM (as constituents of weight) and WC are risk factors for AF. However, the independent relevance of general adiposity for AF was more limited in men than in women. The relevance of both WC and LM suggests a potentially important role for visceral adiposity and muscle mass in AF development.

Application of Machine Learning Methods to Analyze Occurrence and Clinical Features of Ascending Aortic Dilatation in Patients with and without Bicuspid Aortic Valve

Aortic aneurysm (AA) rapture is one of the leading causes of death worldwide. Unfortunately, the diagnosis of AA is often verified after the onset of complications, in most cases after aortic rupture. The aim of this study was to evaluate the frequency of ascending aortic aneurysm (AscAA) and aortic dilatation (AD) in patients with cardiovascular diseases undergoing echocardiography, and to identify the main risk factors depending on the morphology of the aortic valve. We processed 84,851 echocardiographic (ECHO) records of 13,050 patients with aortic dilatation (AD) in the Almazov National Medical Research Centre from 2010 to 2018, using machine learning methodologies. Despite a high prevalence of AD, the main reason for the performed ECHO was coronary artery disease (CAD) and hypertension (HP) in 33.5% and 14.2% of the patient groups, respectively. The prevalence of ascending AD (>40 mm) was 15.4% (13,050 patients; 78.3% (10,212 patients) in men and 21.7% (2838 patients) in women). Only 1.6% (n = 212) of the 13,050 patients with AD knew about AD before undergoing ECHO in our center. Among all the patients who underwent ECHO, we identified 1544 (1.8%) with bicuspid aortic valve (BAV) and 635 with BAV had AD (only 4.8% of all AD patients). According to the results of the random forest feature importance analysis, we identified the eight main factors of AD: age, male sex, vmax aortic valve (AV), aortic stenosis (AS), blood pressure, aortic regurgitation (AR), diabetes mellitus, and heart failure (HF). The known factors of AD-like HP, CAD, hyperlipidemia, BAV, and obesity, were also AD risk factors, but were not as important. Our study showed a high frequency of AscAA and dilation. Standard risk factors of AscAA such as HP, hyperlipidemia, or obesity are significantly more common in patients with AD, but the main factors in the formation of AD are age, male sex, vmax AV, blood pressure, AS, AR, HF, and diabetes mellitus. In males with BAV, AD incidence did not differ significantly, but the presence of congenital heart disease was one of the 12 main risk factors for the formation of AD and association with more significant aortic dilatation in AscAA groups.

How does childhood maltreatment influence cardiovascular disease? A sequential causal mediation analysis

BACKGROUND

Childhood maltreatment has been consistently associated with cardiovascular disease (CVD). However, the mechanisms of this relationship are not yet fully understood. We explored the relative contribution of anxiety/depression, smoking, body mass index (BMI) and inflammation (C-reactive protein, CRP) to the association between childhood maltreatment and CVD in men and women aged 40-69 years in the UK.

METHODS

We used data from 40 596 men and 59 511 women from UK Biobank. To estimate the indirect effects of childhood maltreatment (physical, sexual and emotional abuse, and emotional and physical neglect) on incident CVD via each of the mediators, we applied a sequential mediation approach.

RESULTS

All forms of maltreatment were associated with increased CVD risk [hazard ratios (HRs) ranging from 1.09 to 1.27]. Together, anxiety/depression, smoking, BMI and inflammation (indexed by CRP) mediated 26-90% of the association between childhood maltreatment and CVD, and the contribution of these mediators differed by type of maltreatment and sex. Anxiety/depression mediated the largest proportion of the association of sexual abuse, emotional abuse and emotional neglect with CVD (accounting for 16-43% of the total effect), especially in women. In men, BMI contributed the most to the indirect effect of associations of physical abuse and physical neglect with CVD; in women, anxiety/depression and BMI had similar contributions.

CONCLUSIONS

These findings add to the understanding of how childhood maltreatment affects CVD risk and identify modifiable mediating factors that could potentially reduce the burden of CVD in people exposed to maltreatment in early life.

A phenome-wide bidirectional Mendelian randomization analysis of atrial fibrillation

Background

The prevalence of atrial fibrillation (AF) is increasing with an aging worldwide population, yet a comprehensive understanding of its causes and consequences remains limited. We aim to assess the causes and consequences of AF via a bidirectional Mendelian randomization (MR) analysis.

Methods

We used publicly available genome-wide association study (GWAS) summary data, centralized and harmonized by an open GWAS database. We assessed the genetically predicted effects of 5048 exposures on risk of AF, and the genetically predicted effects of genetic liability to AF, on 10 308 outcomes via two-sample MR analysis. Multivariable MR analysis was further conducted to explore the comparative roles of identified risk factors.

Results

MR analysis suggested that 55 out of 5048 exposure traits, including four proteins, play a causal role in AF (P <1e-5 allowing for multiple comparisons). Multivariable analysis suggested that higher body mass index, height and systolic blood pressure as well as genetic liability to coronary artery diseases independently cause AF. Three out of the four proteins (DUSP13, TNFSF12 and IL6R) had a drug prioritizing score for atrial fibrillation of 0.26, 0.38 and 0.88, respectively (values closer to 1 indicating stronger evidence of the protein as a potential drug target). Genetic liability to AF was linked to a higher risk of cardio-embolic ischaemic stroke.

Conclusions

Our results suggest body mass index, height, systolic blood pressure and genetic liability to coronary artery disease are independent causal risk factors for AF. Several proteins, including DUSP13, IL-6R and TNFSF12, may have therapeutic potential for AF.

Low MICA Gene Expression Confers an Increased Risk of Graves' Disease: A Mendelian Randomization Study

Background: Expression of natural killer group 2 member D (NKG2D) ligand (NKG2DL) plays a major role as a "danger signal" on stressed cells to promote removal of the latter by NKG2D-expressing cytotoxic lymphocytes. NKG2DL expression has been found in peripheral immune cells as well, such as in macrophages; however, the effect of this expression is yet to be determined. Methods: We determined instrumental variables (IVs; R² <0.01 in linkage disequilibrium), explaining the major variance in major histocompatibility complex class I chain-related protein A (MICA) and B (MICB) gene expression levels from the expression-quantitative trait locus (eQTL) of NKG2DLs based on the RNA-seq analysis of peripheral blood mononuclear cells (PBMCs) from 381 Japanese. Simultaneously, the target outcomes were filtered by PheWAS from 58 health risks, using a community-based cohort study composed of 44,739 Japanese residents. Finally, we estimated the causal effect of gene expression levels on the outcomes using the Mendelian randomization approach. Results: We determined nine and four IVs, explaining 87.6% and 33.0% of MICA and MICB gene expression levels, respectively. In the association test, we identified 10 or 13 significant outcomes associated with the MICA or MICB eQTLs, respectively, as well as the causal effect of MICA expression on Graves' disease (GD) (p = 4.2 × 10^-3; odds ratio per 1 S.D. difference in the expression: 0.983 [confidence interval: 0.971-0.995]), using the weighted median estimator, without significant pleiotropy (p > 0.05), and the results were consistent across the sensitivity analyses. Conclusions: Our study provide novel evidence associating NKG2DL expression with GD, an autoimmune thyroiditis; direction of the effect indicated the immunoregulatory role of MICA expression in PBMCs, suggesting the importance of further functional assays in inflammatory diseases.

Inflammatory Burden and Immunomodulative Therapeutics of Cardiovascular Diseases

Phenotyping cardiovascular illness and recognising heterogeneities within are pivotal in the contemporary era. Besides traditional risk factors, accumulated evidence suggested that a high inflammatory burden has emerged as a key characteristic modulating both the pathogenesis and progression of cardiovascular diseases, inclusive of atherosclerosis and myocardial infarction. To mechanistically elucidate the correlation, signalling pathways downstream to Toll-like receptors, nucleotide oligomerisation domain-like receptors, interleukins, tumour necrosis factor, and corresponding cytokines were raised as central mechanisms exerting the effect of inflammation. Other remarkable adjuvant factors include oxidative stress and secondary ferroptosis. These molecular discoveries have propelled pharmaceutical advancements. Statin was suggested to confer cardiovascular benefits not only by lowering cholesterol levels but also by attenuating inflammation. Colchicine was repurposed as an immunomodulator co-administered with coronary intervention. Novel interleukin-1β and −6 antagonists exhibited promising cardiac benefits in the recent trials as well. Moreover, manipulation of gut microbiota and associated metabolites was addressed to antagonise inflammation-related cardiovascular pathophysiology. The gut-cardio-renal axis was therein established to explain the mutual interrelationship. As for future perspectives, artificial intelligence in conjunction with machine learning could better elucidate the sequencing of the microbiome and data mining. Comprehensively understanding the interplay between the gut microbiome and its cardiovascular impact will help identify future therapeutic targets, affording holistic care for patients with cardiovascular diseases.

Pathophysiological pathways related to high plasma GDF-15 concentrations in patients with heart failure

AIMS

Elevated concentrations of Growth Differentiation factor 15 (GDF-15) in patients with heart failure (HF) have been consistently associated with worse clinical outcomes, but what disease mechanisms high GDF-15 concentrations represent remains unclear. Here, we aim to identify activated pathophysiological pathways related to elevated GDF-15 expression in patients with HF.

METHODS AND RESULTS

In 2279 patients with HF, we measured circulating levels of 363 biomarkers. Then, we performed a pathway over-representation analysis to identify key biological pathways between patients in the highest and lowest GDF-15 concentration quartiles. Data were validated in an independent cohort of 1705 patients with HF. In both cohorts, the strongest up-regulated biomarkers in those with high GDF-15 were fibroblast growth factor 23 (FGF-23), death receptor 5 (TRAIL-R2), WNT1-inducible-signaling pathway protein 1 (WISP-1), TNF Receptor Superfamily Member 11a (TNFRSF11A), leukocyte immunoglobulin-like receptor subfamily B member 4 (LILRB4), and Trefoil Factor 3 (TFF3). Pathway over-representation analysis revealed that high GDF-15 patients had increased activity of pathways related to inflammatory processes, notably positive regulation of chemokine production; response to interleukin 6 (IL-6); tumour necrosis factor (TNF) and death receptor activity; and positive regulation of T cell differentiation and inflammatory response. Furthermore, we found pathways involved in regulation of insulin-like growth factor (IGF) receptor signalling and regulatory pathways of tissue, bones, and branching structures. GDF-15 quartiles significantly predicted all-cause mortality and HF hospitalization.

CONCLUSION

Patients with HF and high plasma concentrations of GDF-15 are characterized by increased activation of inflammatory pathways and pathways related to IGF-1 regulation and bone/tissue remodelling.

Are Alzheimer's and coronary artery diseases genetically related to longevity?

INTRODUCTION

In the last decade researchers have attempted to investigate the shared genetic architecture of longevity and age-related diseases and assess whether the increased longevity in certain people is due to protective alleles in the risk genes for a particular condition or whether there are specific "longevity" genes increasing the lifespan independently of age-related conditions' risk genes. The aim of this study was to investigate the shared genetic component between longevity and two age-related conditions.

METHODS

We performed a cross-trait meta-analysis of publicly available genome-wide data for Alzheimer's disease, coronary artery disease and longevity using a subset-based approach provided by the R package ASSET.

RESULTS

Despite the lack of strong genetic correlation between longevity and the two diseases, we identified 38 genome-wide significant lead SNPs across 22 independent genomic loci. Of them 6 were found to be potentially shared among the three traits mapping to genes including DAB2IP, DNM2, FCHO1, CLPTM1, and SNRPD2. We also identified 19 novel genome-wide associations for the individual traits in this study. Functional annotations and biological pathway enrichment analyses suggested that pleiotropic variants are involved in clathrin-mediated endocytosis and plasma lipoprotein and neurotransmitter clearance processes.

DISCUSSION

In summary, we have been able to advance in the knowledge of the genetic overlap existing among longevity and the two most common age-related disorders.

A trans-omic Mendelian randomization study of parental lifespan uncovers novel aging biology and therapeutic candidates for chronic diseases

The study of parental lifespan has emerged as an innovative tool to advance aging biology and our understanding of the genetic architecture of human longevity and aging-associated diseases. Here, we leveraged summary statistics of a genome-wide association study including over one million parental lifespans to identify genetically regulated genes from the Genotype-Tissue Expression project. Through a combination of multi-tissue transcriptome-wide association analyses and genetic colocalization, we identified novel genes that may be associated with parental lifespan. Mendelian randomization (MR) analyses also identified circulating proteins and metabolites causally associated with parental lifespan and chronic diseases offering new drug repositioning opportunities such as those targeting apolipoprotein-B-containing lipoproteins. Liver expression of HP, the gene encoding haptoglobin, and plasma haptoglobin levels were causally linked with parental lifespan. Phenome-wide MR analyses were used to map genetically regulated genes, proteins and metabolites with other human traits as well as the disease-related phenome in the FinnGen cohorts (n = 135,638). Altogether, this study identified new candidate genes, circulating proteins and metabolites that may influence human aging as well as potential therapeutic targets for chronic diseases that warrant further investigation.

Inborn errors of IL-6 family cytokine responses

The IL-6 family of cytokines mediates functions in host protective immunity, development of multiple organs, tissue regeneration and metabolism. Inborn errors in cytokines or cytokine receptor units highlight specific roles for IL-6, IL-11, LIF, OSM, and CLC signaling whereas incomplete loss-of-function variants in the common receptor chain GP130 encoded by IL6ST or the transcription factor STAT3, as well as genes that affect either GP130 glycosylation (PGM3) or STAT3 transcriptional control (ZNF341) lead to complex phenotypes including features of hyper-IgE syndrome. Gain-of-function variants in the GP130-STAT3 signaling pathway cause immune dysregulation disorders. Insights into IL-6 family cytokine signaling inform on therapeutic application in immune-mediated disorders and potential side effects such as infection susceptibility.

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

Objectives

To find out the genetic association between IL6 and autoimmune arthritis.

Methods

We performed a two-sample Mendelian randomization (MR) study using multiple genome-wide association studies (GWAS) datasets. Furthermore, a sex-stratified MR study was performed to identify sexual dimorphism in the association between IL6 and autoimmune arthritis. Then, LocusZoom plots were displayed based on the IL6R gene region to present evidence of genetic colocalization between diseases.

Results

The MR result denoted a genetic association between the increased level of IL-6 signaling and risk of RA (β=0.325, 95%CI 0.088, 0.561, p=7.08E-03) and AS (β=1.240, 95%CI 0.495, 1.980, p=1.1E-03). Accordingly, sIL6R was found to have negatively correlation with the onset of RA (β=-0.020, 95%CI -0.0320, -0.008, p=1.18E-03) and AS (β=-0.125, 95%CI -0.177, -0.073, p=2.29E-06). However, no genetic association between IL6/sIL6R and PsA was detected. The gender-stratified MR analysis showed that IL6 was associated with AS in the male population, with RA in the female population, and with PsA in the male population. Additionally, ADAR, a gene identified by a sensitive test, could be the reason for the nonsignificant association between IL6 and PsA in a pooled population.

Conclusion

Our findings showed that the overactive IL6 signal pathway led to autoimmune arthritis, especially in RA and AS. Sexual difference was also observed in IL6-intermediate susceptibility to autoimmune arthritis.

Causal risk and protective factors in rheumatoid arthritis: A genetic update

The characterization of risk and protective factors in complex diseases such as rheumatoid arthritis (RA) has evolved from epidemiological studies, which test association, to the use of Mendelian randomization approaches, which test direct relationships. Indeed, direct associations with the mucosal origin of RA are retrieved with periodontal disease (Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans predominantly), interstitial lung involvement, tobacco smoking and air pollutants. Next, factors directly associated with an acquired immune response include genetic factors (HLA DRB1, PTPN22), capacity to produce anti-modified protein antibodies (AMPA), and relatives with a history of autoimmune diseases. Finally, factors can be also classified according to their direct capacity to interfere with the IL-6/CRP/sIL-IL6R proinflammatory pathway as risk factor (body fat, cardiometabolic factors, type 2 diabetes, depressive syndrome) or either as protective factors by controlling of sIL-6R levels (higher education level, and intelligence). Although some co-founders have been characterized (e.g. vitamin D, physical activity, cancer) the direct association with sex-discrepancy, pregnancy, and infections among other factors remains to be better explored.

miR-21 and miR-146a: The microRNAs of inflammaging and age-related diseases

The first paper on "inflammaging" published in 2001 paved the way for a unifying theory on how and why aging turns out to be the main risk factor for the development of the most common age-related diseases (ARDs). The most exciting challenge on this topic was explaining how systemic inflammation steeps up with age and why it shows different rates among individuals of the same chronological age. The "epigenetic revolution" in the past twenty years conveyed that the assessment of the individual genetic make-up is not enough to depict the trajectories of age-related inflammation. Accordingly, others and we have been focusing on the role of non-coding RNA, i.e. microRNAs (miRNAs), in inflammaging. The results obtained in the latest 10 years underpinned the key role of a miRNA subset that we have called inflammamiRs, owing to their ability to master (NF-κB)-driven inflammatory pathways. In this review, we will focus on two inflammamiRs, i.e. miR-21-5p and miR-146a-5p, which target a variety of molecules belonging to the NF-κB/NLRP3 pathways. The interplay between miR-146a-5p and IL-6 in the context of aging and ARDs will also be highlighted. We will also provide the most relevant evidence suggesting that circulating inflammamiRs, along with IL-6, can measure the degree of inflammaging.

Evaluating the Causal Association Between Educational Attainment and Asthma Using a Mendelian Randomization Design

Asthma is a common chronic respiratory disease. In the past 10 years, genome-wide association study (GWAS) has been widely used to identify the common asthma genetic variants. Importantly, these publicly available asthma GWAS datasets provide important data support to investigate the causal association of kinds of risk factors with asthma by a Mendelian randomization (MR) design. It is known that socioeconomic status is associated with asthma. However, it remains unclear about the causal association between socioeconomic status and asthma. Here, we selected 162 independent educational attainment genetic variants as the potential instruments to evaluate the causal association between educational attainment and asthma using large-scale GWAS datasets of educational attainment (n = 405,072) and asthma (n = 30,810). We conducted a pleiotropy analysis using the MR-Egger intercept test and the MR pleiotropy residual sum and outlier (MR-PRESSO) test. We performed an MR analysis using inverse-variance weighted, weighted median, MR-Egger, and MR-PRESSO. The main analysis method inverse-variance weighted indicated that each 1 standard deviation increase in educational attainment (3.6 years) could reduce 35% asthma risk [odds ratio (OR) = 0.65, 95% confidence interval (CI) 0.51–0.85, P = 0.001]. Importantly, evidence from other MR methods further supported this finding, including weighted median (OR = 0.55, 95% CI 0.38–0.80, P = 0.001), MR-Egger (OR = 0.48, 95% CI 0.16–1.46, P = 0.198), and MR-PRESSO (OR = 0.65, 95% CI 0.51–0.85, P = 0.0015). Meanwhile, we provide evidence to support that educational attainment protects against asthma risk dependently on cognitive performance using multivariable MR analysis. In summary, we highlight the protective role of educational attainment against asthma. Our findings may have public health applications and deserve further investigation.

Low expression of IL6R predicts poor prognosis for lung adenocarcinoma

Background

Interleukin 6 (IL6) is both a pleiotropic cytokine and an immune-related gene. Interleukin 6 receptor (IL6R) is the receptor for IL6. It may be closely connected to the development of lung cancer. This research aims to explore the prognostic value of IL6R and prevent overtreatment of patients with lung adenocarcinoma (LUAD).

Methods

In this study, the expression of IL6R in tumor tissues and surrounding tissues was first analyzed by immunohistochemistry in the Affiliated Hospital of Nantong University (NTU) cohort. Secondly, we downloaded information from The Cancer Genome Atlas (TCGA) for the TCGA cohort and used this information to explore the messenger RNA (mRNA) level of IL6R. We then used Kaplan-Meier survival analyses, univariate and multivariate Cox analyses, nomogram models, and decision curve analyses to assess the prognostic value of IL6R. In addition, we also analyzed immune cell infiltration and the signaling pathways related to IL6R through Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA).

Results

Through the data analysis of the NTU cohort and the TCGA cohort, it was found that the expression of IL6R in normal tissues around the tumor was higher than that in tumor tissue, and was positively correlated with the overall survival (OS) of LUAD patients. Additionally, low expression of IL6R was found to be an independent predictor of poor prognosis among the patients in these two research cohorts. Next, using GO, KEGG, and GSEA analyses, we found that partially infiltrated tumor immune cells might be related to earlier staging and better prognosis of patients with LUAD. Finally, the study of the 3-5-year survival rate of LUAD patients through the nomogram showed that the expression of IL6R could improve the accuracy of prediction to prevent the overtreatment of some LUAD patients.

Conclusions

In summary, our study indicated that the low expression of IL6R was associated with poor prognosis among LUAD patients and that low expression of IL6R is a potential independent risk factor that could provide a basis for strengthening postoperative classification management of such patients.

Unravelling the broader complexity of IL-6 involvement in health and disease

The classification of interleukin-6 (IL-6) as a pro-inflammatory cytokine undervalues the biological impact of this cytokine in health and disease. With broad activities affecting the immune system, tissue homeostasis and metabolic processes, IL-6 displays complex biology. The significance of these involvements has become increasingly important in clinical settings where IL-6 is identified as a prominent target for therapy. Here, clinical experience with IL-6 antagonists emphasises the need to understand the context-dependent properties of IL-6 within an inflammatory environment and the anticipated or unexpected consequences of IL-6 blockade. In this review, we will describe the immunobiology of IL-6 and explore the gamut of IL-6 bioactivity affecting the clinical response to biological drugs targeting this cytokine pathway.

Mendelian Randomization Studies in Stroke: Exploration of Risk Factors and Drug Targets With Human Genetic Data

Elucidating the causes of stroke is key to developing effective preventive strategies. The Mendelian randomization approach leverages genetic variants related to an exposure of interest to investigate the effects of varying that exposure on disease risk. The random allocation of genetic variants at conception reduces confounding from environmental factors and thus strengthens causal inference, analogous to treatment allocation in a randomized controlled trial. With the recent explosion in the availability of human genetic data, Mendelian randomization has proven a valuable tool for studying risk factors for stroke. In this review, we provide an overview of recent developments in the application of Mendelian randomization to unravel the pathophysiology of stroke subtypes and identify therapeutic targets for clinical translation. The approach has offered novel insight into the differential effects of risk factors and antihypertensive, lipid-lowering, and anticoagulant drug classes on risk of stroke subtypes. Analyses have further facilitated the prioritization of novel drug targets, such as for inflammatory pathways underlying large artery atherosclerotic stroke and for the coagulation cascade that contributes to cardioembolic stroke. With continued methodological advances coupled with the rapidly increasing availability of genetic data related to a broad range of stroke phenotypes, the potential for Mendelian randomization in this context is expanding exponentially.

IL6 trans-signaling associates with ischemic stroke but not with atrial fibrillation

BACKGROUND

Pro-inflammatory processes underlie ischemic stroke, albeit it is largely unknown if they selectively associate with the risk of atherothrombotic or cardioembolic ischemic stroke. Here we analyze whether pro-inflammatory interleukin (IL) 6 trans-signaling, is associated with the risk of ischemic stroke and underlying atrial fibrillation (AF).

METHODS

During a 20-year follow-up, 203 incident ischemic strokes were recorded from national registers in the cohort of 60-year-old men and women from Stockholm (n = 4232). The risk of ischemic stroke associated with circulating IL6 trans-signaling, assessed by a ratio between the pro-inflammatory binary IL6:sIL6R complex and the inactive ternary IL6:sIL6R:sgp130 complex (B/T ratio), was estimated by Cox regression and expressed as hazard ratio (HR) with a 95% confidence interval (CI) in the presence or absence of AF. Risk estimates were adjusted for cardiovascular risk factors and anticoagulant treatment. In a secondary analysis, the association of IL6 trans-signaling with the risk of incident AF (n = 279) was analyzed.

RESULTS

B/T ratio > median was associated with increased risk of ischemic stroke in study participants without AF (adjusted HR 1.49; 95% CI 1.08-2.06), while an association could not be demonstrated in the presence of AF. Moreover, the B/T ratio was not associated with the risk of AF (HR 0.96; 95% CI 0.75-1.24).

CONCLUSIONS

Pro-inflammatory IL6 trans-signaling, estimated by the B/T ratio, is associated with ischemic stroke in individuals without AF. These findings suggest that the B/T ratio could be used to assess the risk of non-AF associated ischemic stroke.