Additive Effects of Genetic Interleukin-6 Signaling Downregulation and Low-Density Lipoprotein Cholesterol Lowering on Cardiovascular Disease: A 2×2 Factorial Mendelian Randomization Analysis

Exploring the role of interleukin-6 receptor blockade in epilepsy and associated neuropsychiatric conditions through a mendelian randomization study

BACKGROUND

The interplay between inflammation, immune dysregulation, and the onset of neurological disorders, including epilepsy, has become increasingly recognized. Interleukin (IL)-6, a pro-inflammatory cytokine, is suspected to not only mediate traditional inflammatory pathways but also contribute to neuroinflammatory responses that could underpin neuropsychiatric symptoms and broader psychiatric disorders in epilepsy patients. The role of IL-6 receptor (IL6R) blockade presents an intriguing target for therapeutic intervention due to its potential to attenuate these processes.

AIM

To explore the potential of IL6R blockade in reducing the risk of epilepsy and investigate whether this pathway might also influence associated psychiatric and neuropsychiatric conditions due to neuroinflammation.

METHODS

Mendelian randomization (MR) analysis employing single nucleotide polymorphisms (SNPs) in the vicinity of the IL6R gene (total individuals = 408225) was used to evaluate the putative causal relationship between IL6R blockade and epilepsy (total cases/controls = 12891/312803), focal epilepsy (cases/controls = 7526/399290), and generalized epilepsy (cases/controls = 1413/399287). SNP weights were determined by their effect on C-reactive protein (CRP) levels and integrated using inverse variance-weighted meta-analysis as surrogates for IL6R effects. To address potential outlier and pleiotropic influences, sensitivity analyses were conducted employing a variety of MR methods under different modeling assumptions.

RESULTS

The genetic simulation targeting IL6R blockade revealed a modest but significant reduction in overall epilepsy risk [inverse variance weighting: Odds ratio (OR): 0.827; 95% confidence interval (CI): 0.685-1.000; P = 0.05]. Subtype analysis showed variability, with no significant effect observed in generalized, focal, or specific childhood and juvenile epilepsy forms. Beyond the primary inflammatory marker CRP, the findings also suggested potential non-inflammatory pathways mediated by IL-6 signaling contributing to the neurobiological landscape of epilepsy, hinting at possible links to neuroinflammation, psychiatric symptoms, and associated mental disorders.

CONCLUSION

The investigation underscored a tentative causal relationship between IL6R blockade and decreased epilepsy incidence, likely mediated via complex neuroinflammatory pathways. These results encouraged further in-depth studies involving larger cohorts and multifaceted psychiatric assessments to corroborate these findings and more thoroughly delineate the neuro-psychiatric implications of IL-6 signaling in epilepsy. The exploration of IL6R blockade could herald a novel therapeutic avenue not just for seizure management but also for addressing the broader psychiatric and cognitive disturbances often associated with epilepsy.

Genetically proxied IL-6 signaling and risk of Alzheimer's disease and lobar intracerebral hemorrhage: A drug target Mendelian randomization study

INTRODUCTION

Evidence suggests that higher C-reactive protein (CRP) is associated with lower risk of Alzheimer's disease (AD) and lobar intracerebral hemorrhage (ICH). Whether interleukin (IL)-6 signaling, an active pharmacological target upstream of CRP, is associated with these amyloid-related pathologies remains unknown.

METHODS

We used 26 CRP-lowering variants near the IL-6 receptor gene to perform Mendelian randomization analyses for AD (111,326 cases, 677,663 controls) and ICH (1545 cases, 1481 controls). We explored the effect of genetically proxied IL-6 signaling on serum, cerebrospinal fluid (CSF), and brain proteome (971 individuals).

RESULTS

Genetically upregulated IL-6 receptor-mediated signaling was associated with lower risk of AD (OR per increment in serum logCRP levels: 0.87, 95% CI: 0.79-0.95) and lobar ICH (OR: 0.27, 95% CI: 0.09-0.89). We also found associations with 312, 77, and 79 brain, CSF, and plasma proteins, respectively, some of which were previously implicated in amyloid-clearing mechanisms.

DISCUSSION

Genetic data support that CRP-lowering through variation in the gene encoding IL-6 receptor may be associated with amyloid-related outcomes.

Highlights

Genetic variants proxying IL-6 inhibition are associated with AD and lobar ICH risk.The variants are also associated with amyloid clearing-related proteomic changes.Whether pharmacologic IL-6 inhibition is linked to AD or lobar ICH merits further study.

Genetic perturbation of IL-6 receptor signaling pathway and risk of multiple respiratory diseases

Dysregulation of inflammation can lead to multiple chronic respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma. Interleukin-6 (IL6) is crucial in regulating the inflammatory cascade, but the causal link between IL6 signaling downregulation and respiratory diseases risk is unclear. This study uses Mendelian randomization to examine the effects of IL6R blockade on respiratory diseases. Analyzing data from 522,681 Europeans, 26 genetic variants were obtained to mimic IL6R inhibition. Our findings show that IL6R blockade significantly reduces the risk of COPD (OR = 0.71, 95% CI = 0.60-9.84) and asthma (OR = 0.82, 95% CI = 0.74-0.90), with protective trends for bronchitis, pulmonary embolism, and lung cancer. Results were consistent across methods, with no significant heterogeneity or pleiotropy. These insights suggest IL6R downregulation as a potential therapeutic target for respiratory diseases, meriting further clinical investigation.

CETP and SGLT2 inhibitor combination therapy increases glycemic control: a 2x2 factorial Mendelian randomization analysis

Introduction

Cholesteryl ester transfer protein (CETP) inhibitors, initially developed for treating hyperlipidemia, have shown promise in reducing the risk of new-onset diabetes during clinical trials. This positions CETP inhibitors as potential candidates for repurposing in metabolic disease treatment. Given their oral administration, they could complement existing oral medications like sodium-glucose cotransporter 2 (SGLT2) inhibitors, potentially delaying the need for injectable therapies such as insulin.

Methods

We conducted a 2x2 factorial Mendelian Randomization analysis involving 233,765 participants from the UK Biobank. This study aimed to evaluate whether simultaneous genetic inhibition of CETP and SGLT2 enhances glycemic control compared to inhibiting each separately.

Results

Our findings indicate that dual genetic inhibition of CETP and SGLT2 significantly reduces glycated hemoglobin levels compared to controls and single-agent inhibition. Additionally, the combined inhibition is linked to a lower incidence of diabetes compared to both the control group and SGLT2 inhibition alone.

Discussion

These results suggest that combining CETP and SGLT2 inhibitor therapies may offer superior glycemic control over SGLT2 inhibitors alone. Future clinical trials should investigate the potential of repurposing CETP inhibitors for metabolic disease treatment, providing an oral therapeutic option that could benefit high-risk patients before they require injectable therapies like insulin or glucagon-like peptide-1 (GLP-1) receptor agonists.

Interleukin-6 signaling pathway in Mendelian randomization: A 10-year bibliometric analysis

Interleukin 6 (IL-6), a pleiotropic cytokine, is crucial in a variety of inflammatory and immunological disorders. In recent years, mendelian randomization, which is a widely used and successful method of analyzing causality, has recently been investigated for the relationship between the IL-6 pathway and related diseases. However, no studies have been conducted to review the research hotspots and trends in the field of IL-6 signaling pathway in Mendelian randomization. In this study, the Web of Science Core Collection (WoSCC) served as our literature source database to gather articles about the IL-6 signaling pathway in Mendelian randomization from 2013 to 2023. VOSviewer (version 1.6.18), Microsoft Excel 2021, and Scimago Graphica were employed for bibliometric and visualization analysis. A total of 164 documents that were written by 981 authors coming from 407 institutions across 41 countries and published in 107 journals were located from January 2013 to August 2023. With 64 and 25, respectively, England and the University of Bristol had the highest number of publications. Frontiers in Immunology is the most prolific journal, and Golam M Khandaker has published the highest number of significant articles. The most co-cited article was an article entitled the interleukin-6 receptor as a target for prevention of coronary-heart-disease: a Mendelian randomization analysis, written by Daniel I Swerdlow. The most popular keywords were "mendelian randomization," "interleukin-6," "il-6," "c-reactive protein," "association," "coronary-heart-disease," "inflammation," "instruments," "risk," "rheumatoid arthritis," "depression." The full extent of the existing literature over the last 10 years is systematically revealed in this study, which can provide readers with a valuable reference for fully comprehending the research hotspots and trends in the field of IL-6 signaling pathway in Mendelian randomization.

Proteogenomic Data Integration Reveals CXCL10 as a Potentially Downstream Causal Mediator for IL-6 Signaling on Atherosclerosis

BACKGROUND

Genetic and experimental studies support a causal involvement of IL-6 (interleukin-6) signaling in atheroprogression. Although trials targeting IL-6 signaling are underway, any benefits must be balanced against an impaired host immune response. Dissecting the mechanisms that mediate the effects of IL-6 signaling on atherosclerosis could offer insights about novel drug targets with more specific effects.

METHODS

Leveraging data from 522 681 individuals, we constructed a genetic instrument of 26 variants in the gene encoding the IL-6R (IL-6 receptor) that proxied for pharmacological IL-6R inhibition. Using Mendelian randomization, we assessed its effects on 3281 plasma proteins quantified with an aptamer-based assay in the INTERVAL cohort (n=3301). Using mediation Mendelian randomization, we explored proteomic mediators of the effects of genetically proxied IL-6 signaling on coronary artery disease, large artery atherosclerotic stroke, and peripheral artery disease. For significant mediators, we tested associations of their circulating levels with incident cardiovascular events in a population-based study (n=1704) and explored the histological, transcriptomic, and cellular phenotypes correlated with their expression levels in samples from human atherosclerotic lesions.

RESULTS

We found significant effects of genetically proxied IL-6 signaling on 70 circulating proteins involved in cytokine production/regulation and immune cell recruitment/differentiation, which correlated with the proteomic effects of pharmacological IL-6R inhibition in a clinical trial. Among the 70 significant proteins, genetically proxied circulating levels of CXCL10 (C-X-C motif chemokine ligand 10) were associated with risk of coronary artery disease, large artery atherosclerotic stroke, and peripheral artery disease, with up to 67% of the effects of genetically downregulated IL-6 signaling on these end points mediated by decreases in CXCL10. Higher midlife circulating CXCL10 levels were associated with a larger number of cardiovascular events over 20 years, whereas higher CXCL10 expression in human atherosclerotic lesions correlated with a larger lipid core and a transcriptomic profile reflecting immune cell infiltration, adaptive immune system activation, and cytokine signaling.

CONCLUSIONS

Integrating multiomics data, we found a proteomic signature of IL-6 signaling activation and mediators of its effects on cardiovascular disease. Our analyses suggest the interferon-γ-inducible chemokine CXCL10 to be a potentially causal mediator for atherosclerosis in 3 vascular compartments and, as such, could serve as a promising drug target for atheroprotection.

Causal association between lipoproteins and risk of coronary artery disease-a systematic review and meta-analysis of Mendelian randomization studies

OBJECTIVE

To systematically evaluate the causal effect of lipoproteins to the risk of coronary artery disease (CAD) by systematic review and meta-analysis of the associated Mendelian randomization (MR) studies.

METHODS

This systematic review was registered in PROSPERO (ID CRD42023465430). Searches from the databases (e.g., PubMed, Embase, Cochrane, Web of Science) and non-database sources to collect MR studies. The search time frame was from the database inception to August 2023. After data extraction, quality evaluation was performed, and the meta-analysis with bias evaluation was carried out with RevMan software.

RESULTS

A total of 5,828,409 participants from 21 records were included. Quality and bias assessment was performed by evaluating the internal three assumptions of MR studies. Meta-analysis for the causal association between non-HDL lipoproteins and CAD showed a significantly positive association between LDL and CAD (OR 1.37, 95% CI 1.26-1.49; P < 0.001, I2 = 95%), apoB and CAD (OR 1.38, 95% CI 1.11-1.71; P = 0.003, I2 = 98%), and Lp(a) and CAD (OR 1.21, 95% CI 1.12-1.31; P < 0.001, I2 = 99%). Interestingly, although there was no statistical significance in the association between VLDL/apoA1 and CAD (both P > 0.05), the pooled non-HDL lipoproteins showed a significantly positive association with CAD (OR 1.28, 95% CI 1.22-1.34; P < 0.001, I2 = 99%). For the HDL lipoproteins, the pooled OR showed a significantly negative association with CAD (OR 0.84, 95% CI 0.72-0.98; P = 0.002, I2 = 72%). However, the protective effect of HDL on CAD diminished when analyzed together with apoA1 and/or apoB (both P > 0.05). The funnel plot did not show serious publication bias, and sensitivity analysis performed relatively well robustness of the causal association of LDL, apoB, Lp(a), and total cholesterol with CAD.

CONCLUSION

The present meta-analysis suggests an overall effect of causal association between lipoproteins and CAD. Most of the non-HDL lipoproteins (LDL, apoB, Lp(a)) promote CAD, while the protective effect of HDL in CAD still needs to be verified in the future.

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.

Therapeutic potential of single-nucleotide polymorphism-mediated interleukin-6 receptor blockade in cancer treatment: A Mendelian randomization study

Background

Interleukin-6 (IL-6) is a crucial member of the cytokine network and plays a pivotal role in the pathogenesis of various diseases, including cancer. IL-6 receptor (IL-6R) blockade is widely employed as a therapeutic strategy; however, its efficacy in anticancer therapy remains ambiguous.

Methods

An inverse variance-weighted Mendelian randomization (MR) analysis was conducted to assess the causal effects exerted by IL-6R blockade in remediating cancer. Drug-targeted single-nucleotide polymorphisms (SNPs) were introduced within 300 kb of the IL-6R gene. An instrumental variable comprising 26 SNPs represented IL-6 signaling downregulation and C-reactive protein level reduction. Datasets pertaining to the 33 types of cancer investigated in this study were acquired from the FinnGen genome-wide association study.

Results

The selected instrumental variable lowered fibrinogen levels, confirming its ability to mimic IL-6R blockade. IL-6R blockade exhibited therapeutic effects on five different cancer types documented in the FinnGen database (N = 334,364, including 76,781 cancer patients): bladder (odds ratios (OR) = 0.563), laryngeal (OR = 0.293), eye (OR = 0.098), gallbladder (OR = 0.059), and myeloid leukemia (OR = 0.442); however, it simultaneously elevated the risk of developing basal cell carcinoma (OR = 1.312) and melanoma (OR = 1.311). Sensitivity analyses did not alter the primary results.

Conclusion

Therefore, this study aimed to evaluate the potential and efficacy of SNP-based IL-6R blockade in treating cancer.

CETP and SGLT2 inhibitor combination therapy improves glycemic control

Importance

Cholesteryl ester transfer protein (CETP) inhibition has been associated with decreased risk of new-onset diabetes in past clinical trials exploring their efficacy in cardiovascular disease and can potentially be repurposed to treat metabolic disease. Notably, as an oral drug it can potentially be used to supplement existing oral drugs such as sodium-glucose cotransporter 2 (SGLT2) inhibitors before patients are required to take injectable drugs such as insulin.

Objective

To identify whether CETP inhibitors could be used as an oral add-on to SGLT2 inhibition to improve glycemic control.

Design Setting and Participants

2×2 factorial Mendelian Randomization (MR) is performed on the general population of UK Biobank participants with European ancestry.

Exposures

Previously constructed genetic scores for CETP and SGLT2 function are combined in a 2×2 factorial framework to characterize the associations between joint CETP and SGLT2 inhibition compared to either alone.

Main Outcomes and Measures

Glycated hemoglobin and type-2 diabetes incidence.

Results

Data on 233,765 UK Biobank participants suggests that individuals with genetic inhibition of both CETP and SGLT2 have significantly lower glycated hemoglobin levels (mmol/mol) than control (Effect size: -0.136; 95% CI: -0.190 to -0.081; p-value: 1.09E-06), SGLT2 inhibition alone (Effect size: -0.082; 95% CI: -0.140 to -0.024; p-value: 0.00558), and CETP inhibition alone (Effect size: -0.08479; 95% CI: -0.136 to -0.033; p-value: 0.00118). Furthermore, joint CETP and SGLT2 inhibition is associated with decreased incidence of diabetes (log-odds ratio) compared to control (Effect size: -0.068; 95% CI: -0.115 to -0.021; p-value: 4.44E-03) and SGLT2 inhibition alone (Effect size: -0.062; 95% CI: -0.112 to -0.012; p-value: 0.0149).

Conclusions and Relevance

Our results suggest that CETP and SGLT2 inhibitor therapy may improve glycemic control over SGLT2 inhibitors alone. Future clinical trials can explore whether CETP inhibitors can be repurposed to treat metabolic disease and provide an oral therapeutic option to benefit high-risk patients before escalation to injectable drugs such as insulin or glucagon-like peptide 1 (GLP1) receptor agonists.

Downregulation of interleukin 6 signaling might reduce the risk of periodontitis: a drug target Mendelian randomization study

Aim

Interleukin 6 (IL-6) is considered to play a role in the dysbiotic host response in the development of periodontitis. While the inhibition of the IL-6 receptor using monoclonal antibodies is a well-established therapy for some diseases, so far, its potential benefit in patients with periodontitis has not been examined. We tested the association of genetically proxied downregulation of IL-6 signaling with periodontitis to explore whether downregulation of IL-6 signaling could represent a viable treatment target for periodontitis.

Materials and methods

As proxies for IL-6 signaling downregulation, we selected 52 genetic variants in close vicinity of the gene encoding IL-6 receptor that were associated with lower circulating C-reactive protein (CRP) levels in a genome-wide association study (GWAS) of 575 531 participants of European ancestry from the UK Biobank and the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) consortium. Associations with periodontitis were tested with inverse-variance weighted Mendelian randomization in a study of 17 353 cases and 28 210 controls of European descent in the Gene-Lifestyle Interactions in Dental Endpoints (GLIDE) consortium. In addition, the effect of CRP reduction independent of the IL-6 pathway was assessed.

Results

Genetically proxied downregulation of IL-6 signaling was associated with lower odds of periodontitis (odds ratio (OR) = 0.81 per 1-unit decrement in log-CRP levels; 95% confidence interval (CI): [0.66;0.99]; P = 0.0497). Genetically proxied reduction of CRP independent of the IL-6 pathway had a similar effect (OR = 0.81; 95% CI: [0.68; 0.98]; P = 0.0296).

Conclusion

In conclusion, genetically proxied downregulation of IL-6 signaling was associated with lower odds of periodontitis and CRP might be a causal target for the effect of IL-6 on the risk of periodontitis.

Inflammation compared to low-density lipoprotein cholesterol: two different causes of atherosclerotic cardiovascular disease

PURPOSE OF REVIEW

Inflammation is gaining attention as a target for prevention of atherosclerotic cardiovascular disease (ASCVD). The purpose of this review is to compare the evidence for inflammation with the evidence for low-density lipoprotein (LDL) cholesterol in ASCVD.

RECENT FINDINGS

Evidence from human genetic studies and randomized controlled trials implicate the inflammatory pathway from the inflammasome through interleukin (IL)-1 to IL-6 as a cause of ASCVD. Higher levels of IL-6 may lead to proportionally increased risk of ASCVD, and randomized controlled trials of IL-6 inhibitors are underway. The causal evidence for LDL cholesterol in ASCVD is overwhelming and recent important findings instead revolve around development of improved LDL cholesterol lowering therapy through RNA and DNA based therapeutics. Even though some lipid-lowering therapies lower IL-6, the IL-6 inflammatory pathway and LDL cholesterol are two separate causes of ASCVD.

SUMMARY

IL-6 mediated inflammation most likely causes ASCVD, in parallel with LDL cholesterol. However, fewer individuals in the general population are exposed to high IL-6 than high LDL cholesterol. For inflammation, future research should focus on improving efficacy and safety of anti-inflammatory therapy, and for LDL cholesterol, future research should focus on wider and more effective implementation of LDL cholesterol lowering therapy.

The effect of interleukin-6 signaling on severe malaria: A Mendelian randomization analysis

OBJECTIVES

Severe malaria remains a deadly disease for many young children in low- and middle-income countries. Levels of interleukin (IL)-6 have been shown to identify cases of severe malaria and associate with severity, but it is unknown if this association is causal.

METHODS

A single nucleotide polymorphism (SNP; rs2228145) in the IL-6 receptor was chosen as a genetic variant that is known to alter IL-6 signaling. We tested this, then took this forward as an instrument to perform Mendelian randomization (MR) in MalariaGEN, a large cohort study of patients with severe malaria at 11 worldwide sites.

RESULTS

In MR analyses using rs2228145, we did not identify an effect of decreased IL-6 signaling on severe malaria (odds ratio 1.14, 95% confidence interval 0.56-2.34, P = 0.713). The estimates of the association with any severe malaria subphenotype were similarly null, although with some imprecision. Further analyses using other MR approaches had similar results.

CONCLUSION

These analyses do not support a causal role for IL-6 signaling in the development of severe malaria. This result suggests IL-6 may not be causal for severe outcomes in malaria, and that therapeutic manipulation of IL-6 is unlikely to be a suitable treatment for severe malaria.

Proteogenomic integration reveals CXCL10 as a potentially downstream causal mediator for IL-6 signaling on atherosclerosis

Background

Genetic and experimental studies support a causal involvement of interleukin-6 (IL-6) signaling in atheroprogression. While trials targeting IL-6 signaling are underway, any benefits must be balanced against an impaired host immune response. Dissecting the mechanisms that mediate the effects of IL-6 signaling on atherosclerosis could offer insights about novel drug targets with more specific effects.

Methods

Leveraging data from 522,681 individuals, we constructed a genetic instrument of 26 variants in the gene encoding the IL-6 receptor (IL-6R) that proxied for pharmacological IL-6R inhibition. Using Mendelian randomization (MR), we assessed its effects on 3,281 plasma proteins quantified with an aptamer-based assay in the INTERVAL cohort (n=3,301). Using mediation MR, we explored proteomic mediators of the effects of genetically proxied IL-6 signaling on coronary artery disease (CAD), large artery atherosclerotic stroke (LAAS), and peripheral artery disease (PAD). For significant mediators, we tested associations of their circulating levels with incident cardiovascular events in a population-based study (n=1,704) and explored the histological, transcriptomic, and cellular phenotypes correlated with their expression levels in samples from human atherosclerotic lesions.

Results

We found significant effects of genetically proxied IL-6 signaling on 70 circulating proteins involved in cytokine production/regulation and immune cell recruitment/differentiation, which correlated with the proteomic effects of pharmacological IL-6R inhibition in a clinical trial. Among the 70 significant proteins, genetically proxied circulating levels of CXCL10 were associated with risk of CAD, LAAS, and PAD with up to 67% of the effects of genetically downregulated IL-6 signaling on these endpoints mediated by decreases in CXCL10. Higher midlife circulating CXCL10 levels were associated with a larger number of cardiovascular events over 20 years, whereas higher CXCL10 expression in human atherosclerotic lesions correlated with a larger lipid core and a transcriptomic profile reflecting immune cell infiltration, adaptive immune system activation, and cytokine signaling.

Conclusions

Integrating multiomics data, we found a proteomic signature of IL-6 signaling activation and mediators of its effects on cardiovascular disease. Our analyses suggest the interferon-γ-inducible chemokine CXCL10 to be a potentially causal mediator for atherosclerosis in three vascular compartments and as such could serve as a promising drug target for atheroprotection.

Altered IL-6 signalling and risk of tuberculosis disease: a meta-analysis and Mendelian randomisation study

IL-6 responses are ubiquitous in Mycobacterium tuberculosis (Mtb) infections, but their role in determining human tuberculosis (TB) disease risk is unknown. We used single nucleotide polymorphisms (SNPs) in and near the IL-6 receptor (IL6R) gene, focusing on the non-synonymous variant, rs2228145, associated with reduced classical IL-6 signalling, to assess the effect of altered IL-6 activity on TB disease risk. We identified 16 genome wide association studies (GWAS) of TB disease collating 17,982 cases of TB disease and 972,389 controls across 4 continents. Meta-analyses and Mendelian randomisation analyses revealed that reduced classical IL-6 signalling was associated with lower odds of TB disease, a finding replicated using multiple, independent SNP instruments and 2 separate exposure variables. Our findings establish a causal relationship between IL-6 signalling and the outcome of Mtb infection, suggesting IL-6 antagonists do not increase the risk of TB disease and should be investigated as adjuncts in treatment.

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.

Using genetic association data to guide drug discovery and development: Review of methods and applications

Evidence on the validity of drug targets from randomized trials is reliable but typically expensive and slow to obtain. In contrast, evidence from conventional observational epidemiological studies is less reliable because of the potential for bias from confounding and reverse causation. Mendelian randomization is a quasi-experimental approach analogous to a randomized trial that exploits naturally occurring randomization in the transmission of genetic variants. In Mendelian randomization, genetic variants that can be regarded as proxies for an intervention on the proposed drug target are leveraged as instrumental variables to investigate potential effects on biomarkers and disease outcomes in large-scale observational datasets. This approach can be implemented rapidly for a range of drug targets to provide evidence on their effects and thus inform on their priority for further investigation. In this review, we present statistical methods and their applications to showcase the diverse opportunities for applying Mendelian randomization in guiding clinical development efforts, thus enabling interventions to target the right mechanism in the right population group at the right time. These methods can inform investigators on the mechanisms underlying drug effects, their related biomarkers, implications for the timing of interventions, and the population subgroups that stand to gain the most benefit. Most methods can be implemented with publicly available data on summarized genetic associations with traits and diseases, meaning that the only major limitations to their usage are the availability of appropriately powered studies for the exposure and outcome and the existence of a suitable genetic proxy for the proposed intervention.

Therapeutic potential of IL6R blockade for the treatment of sepsis and sepsis-related death: A Mendelian randomisation study

BACKGROUND

Sepsis is characterised by dysregulated, life-threatening immune responses, which are thought to be driven by cytokines such as interleukin 6 (IL-6). Genetic variants in IL6R known to down-regulate IL-6 signalling are associated with improved Coronavirus Disease 2019 (COVID-19) outcomes, a finding later confirmed in randomised trials of IL-6 receptor antagonists (IL6RAs). We hypothesised that blockade of IL6R could also improve outcomes in sepsis.

METHODS AND FINDINGS

We performed a Mendelian randomisation (MR) analysis using single nucleotide polymorphisms (SNPs) in and near IL6R to evaluate the likely causal effects of IL6R blockade on sepsis (primary outcome), sepsis severity, other infections, and COVID-19 (secondary outcomes). We weighted SNPs by their effect on CRP and combined results across them in inverse variance weighted meta-analysis, proxying the effect of IL6RA. Our outcomes were measured in UK Biobank, FinnGen, the COVID-19 Host Genetics Initiative (HGI), and the GenOSept and GainS consortium. We performed several sensitivity analyses to test assumptions of our methods, including utilising variants around CRP and gp130 in a similar analysis. In the UK Biobank cohort (N = 486,484, including 11,643 with sepsis), IL6R blockade was associated with a decreased risk of our primary outcome, sepsis (odds ratio (OR) = 0.80; 95% confidence interval (CI) 0.66 to 0.96, per unit of natural log-transformed CRP decrease). The size of this effect increased with severity, with larger effects on 28-day sepsis mortality (OR = 0.74; 95% CI 0.47 to 1.15); critical care admission with sepsis (OR = 0.48, 95% CI 0.30 to 0.78) and critical care death with sepsis (OR = 0.37, 95% CI 0.14 to 0.98). Similar associations were seen with severe respiratory infection: OR for pneumonia in critical care 0.69 (95% CI 0.49 to 0.97) and for sepsis survival in critical care (OR = 0.22; 95% CI 0.04 to 1.31) in the GainS and GenOSept consortium, although this result had a large degree of imprecision. We also confirm the previously reported protective effect of IL6R blockade on severe COVID-19 (OR = 0.69, 95% CI 0.57 to 0.84) in the COVID-19 HGI, which was of similar magnitude to that seen in sepsis. Sensitivity analyses did not alter our primary results. These results are subject to the limitations and assumptions of MR, which in this case reflects interpretation of these SNP effects as causally acting through blockade of IL6R, and reflect lifetime exposure to IL6R blockade, rather than the effect of therapeutic IL6R blockade.

CONCLUSIONS

IL6R blockade is causally associated with reduced incidence of sepsis. Similar but imprecisely estimated results supported a causal effect also on sepsis related mortality and critical care admission with sepsis. These effects are comparable in size to the effect seen in severe COVID-19, where IL-6 receptor antagonists were shown to improve survival. These data suggest that a randomised trial of IL-6 receptor antagonists in sepsis should be considered.

Associations of genetically predicted IL-6 signaling with cardiovascular disease risk across population subgroups

BACKGROUND

Interleukin 6 (IL-6) signaling is being investigated as a therapeutic target for atherosclerotic cardiovascular disease (CVD). While changes in circulating high-sensitivity C-reactive protein (hsCRP) are used as a marker of IL-6 signaling, it is not known whether there is effect heterogeneity in relation to baseline hsCRP levels or other cardiovascular risk factors. The aim of this study was to explore the association of genetically predicted IL-6 signaling with CVD risk across populations stratified by baseline hsCRP levels and cardiovascular risk factors.

METHODS

Among 397,060 White British UK Biobank participants without known CVD at baseline, we calculated a genetic risk score for IL-6 receptor (IL-6R)-mediated signaling, composed of 26 variants at the IL6R gene locus. We then applied linear and non-linear Mendelian randomization analyses exploring associations with a combined endpoint of incident coronary artery disease, ischemic stroke, peripheral artery disease, aortic aneurysm, and cardiovascular death stratifying by baseline hsCRP levels and cardiovascular risk factors.

RESULTS

The study participants (median age 59 years, 53.9% females) were followed-up for a median of 8.8 years, over which time a total of 46,033 incident cardiovascular events occurred. Genetically predicted IL-6R-mediated signaling activity was associated with higher CVD risk (hazard ratio per 1-mg/dL increment in absolute hsCRP levels: 1.11, 95% CI: 1.06-1.17). The increase in CVD risk was linearly related to baseline absolute hsCRP levels. There was no evidence of heterogeneity in the association of genetically predicted IL-6R-mediated signaling with CVD risk when stratifying the population by sex, age, body mass index, estimated glomerular filtration rate, or systolic blood pressure, but there was evidence of greater associations in individuals with low-density lipoprotein cholesterol ≥ 160 mg/dL.

CONCLUSIONS

Any benefit of inhibiting IL-6 signaling for CVD risk reduction is likely to be proportional to absolute reductions in hsCRP levels. Therapeutic inhibition of IL-6 signaling for CVD risk reduction should therefore prioritize those individuals with the highest baseline levels of hsCRP.