Assessing the causal relationship between genetically determined inflammatory biomarkers and low back pain risk: a bidirectional two-sample Mendelian randomization study

Uncovering Potential Susceptibility Genes for Multiple Sclerosis-Induced Neuropathic Bladder: A Mendelian Randomization Analysis

Despite lacking a genetic explanation for the causal link between multiple sclerosis (MS) and neuropathic bladder (NPB), our study aims to explore this causality and identify novel susceptibility genes for both phenotypes. We performed linkage disequilibrium score regression to assess SNP heritability for both phenotypes. Two-sample bidirectional Mendelian randomization (MR) analyses were conducted to evaluate causal relationships between MS and NPB. We performed pathway enrichment analysis on instrumental SNPs and applied summary-data-based MR (SMR) with protein and expression quantitative trait loci. Candidate susceptibility genes were further examined through colocalization analysis and differential expression studies. Our analyses indicate a substantial genetic contribution to both MS and NPB phenotypes. MR analysis revealed that MS progression increased NPB risk (OR = 1.126; 95% CI. 1.052-1.205; p < 0.001), with no evidence of reverse causality. Pathway analysis highlighted NIK/NF-kappaB signaling and autophagosome maturation as potentially shared mechanisms. SMR (p_FDR < 0.05) and colocalization analyses (PP.H4 > 0.75) identified NFKB1 and STAT3 as candidate susceptibility genes. Transcriptomic analyses confirmed significant differential expression of these genes (p < 0.05) between MS patients and healthy controls. Our findings established a causal relationship between MS progression and NPB risk, with NFKB1 and STAT3 emerging as promising therapeutic targets for MS-induced NPB.

Gene discovery and pleiotropic architecture of chronic pain in a genome-wide association study of >1.2 million individuals

Chronic pain is highly prevalent worldwide, and genome-wide association studies (GWAS) have identified a growing number of chronic pain loci. To further elucidate its genetic architecture, we leveraged data from 1,235,695 European ancestry individuals across three biobanks. In a meta-analytic GWAS, we identified 343 independent loci for chronic pain, 92 of which were new. Sex-specific meta-analyses revealed 115 independent loci (12 of which were new) for males (N = 583,066) and 12 loci (two of which were new) for females (N = 241,266). Multi-omics gene prioritization analyses highlighted 490 genes associated with chronic pain through their effects on brain- and blood-specific regulation. Loci associated with increased risk for chronic pain were also associated with increased risk for multiple other traits, with Mendelian randomization analyses showing that chronic pain was causally associated with psychiatric disorders, substance use disorders, and C-reactive protein levels. Chronic pain variants also exhibited pleiotropic associations with cortical area brain structures. This study expands our knowledge of the genetics of chronic pain and its pathogenesis, highlighting the importance of its pleiotropy with multiple disorders and elucidating its multi-omic pathophysiology.

Exploring the Association Between Immune Cell Phenotypes and Osteoporosis Mediated by Inflammatory Cytokines: Insights from GWAS and Single-Cell Transcriptomics

BACKGROUND

Patients with osteoporosis experience increased fracture risk and decreased quality of life, which pose significant health burdens and financial challenges. Despite established links between immune cell phenotypes and inflammatory cytokines and osteoporosis, the exact mechanism involved remains unclear, and further understanding is needed for effective prevention and treatment.

METHODS

Here, we performed a two-sample Mendelian randomization (MR) study to estimate the causal effects between 731 immune cell types, 91 and 41 inflammatory factors (which may have some overlap), and 5 types of osteoporosis. In subsequent mediation MR analysis, we assessed whether these inflammatory cytokines mediate the causal relationship between immune cell phenotypes and osteoporosis. Additionally, colo- calization analysis was performed using Bayesian colocalization. Single-cell transcriptomic analysis was performed using datasets from osteoporosis patients available in the Gene Expression Omnibus (GEO) database. Subsequently, single-cell sequencing analysis was performed, including dimensionality reduction, clustering, and pathway enrichment, to investigate the underlying mechanisms. Finally, to confirm the critical role of IgD⁺CD24⁺ B cells and IL-17C in osteoporosis, we established vivo dexamethasone-induced osteoporosis model. Micro-CT was used to assess the effectiveness of model establishment. Flow cytometry was performed to determine the proportion of IgD⁺CD24⁺ B cells within lymphocytes in the blood. ELISA and Western blotting were used to measure IL-17C levels in serum and bone tissue. Immunohistochemistry was conducted to evaluate the expression of IL-17C in bone tissue.

RESULTS

This study found that 32 immune cell phenotypes and 38 inflammatory cytokines were significantly associated with osteoporosis. Mediation analysis indicated that IgD+ CD24+ B cells exacerbated the risk of osteoporosis by influencing the levels of interleukin-17C (IL-17C). The mediated effect was 0.07837, accounting for 15.5% of the total effect. Single-cell transcriptome analysis supported that IgD+ CD24+ B cells play a key role in musculoskeletal-related pathways in osteoporosis patients. Additionally, we have demonstrated the significant involvement of IgD⁺CD24⁺ B cells and IL-17C in the osteoporosis disease model.

CONCLUSION

Inflammatory cytokines play a crucial role in the pathogenesis of immunity-related osteoporosis. In particular, IgD+ CD24+ B cell %lymphocyte increase the risk of osteoporosis by modulating the levels of interleukin-17C. Our results provide evidence to support the link between immunity and osteoporosis and offer new therapeutic strategies for targeting inflammatory pathways in immune-mediated osteoporosis.

The causal effects between low back pain and cerebrospinal fluid metabolites: a two-sample Mendelian randomization study

BACKGROUND

Observational studies have shown an association between cerebrospinal fluid (CSF) metabolites and low back pain (LBP), but the causal relationship between these factors remains unclear.

METHODS

We performed a two-sample Mendelian randomization (MR) analysis to examine whether there is a causal relationship between CSF metabolites and LBP. We applied several MR methods, including inverse variance weighting, weighted median, MR-Egger, Wald ratio, and MR-PRESSO, to test the causal relationship and conducted a sensitivity analysis to assess the robustness of the results.

RESULTS

We identified a total of 12 CSF metabolites significantly associated with LBP, of which Bilirubin, 5,6-dihydrothymine, Erythronate, Mannitol/sorbitol, and Butyrate have a potential inhibitory causal effect on LBP risk (p < 0.05). Meanwhile, 2-hydroxyadipate, Gamma-glutamyl-alpha-lysine, Indoleacetate, N-acetylputrescine, Palmitoyl dihydrosphingomyelin, S-methylcysteine, and 2,3-dihydroxy-5-methylthio-4-pentenoate play a causal role in increasing the risk of LBP (p < 0.05). No significant estimates of heterogeneity or pleiotropy were detected.

CONCLUSION

Our study emphasizes the causal relationship between CSF metabolites and LBP risk, providing reference for clinical treatment and prognosis of LBP.

Assessing the causal relationship between CRP, IL-1α, IL-1β, and IL-6 levels and intervertebral disc degeneration: a two-sample Mendelian randomization study

Growing research has suggested an association between chronic inflammation and Intervertebral disc degeneration (IVDD), but whether there is a causal effect remains unknown. This study adopted two-sample Mendelian randomization (MR) approach to explore the etiological role of chronic inflammation in IVDD risk. Here, summary statistics for C-reactive protein (CRP), interleukin (IL)-1 α , IL-1 β , IL-6 expression and IVDD were obtained from genome-wide association studies (GWAS) of European ancestry. MR analyses were conducted by using inverse variance weighted (IVW), Wald Ratio, weighted median, and MR-Egger method. Sensitivity analyses were conducted to assess the robustness of the results. The MR analyses suggested a lack of causal association of CRP, IL-6 , and IL-1 α levels on IVDD (CRP-IVDD: odds ratio [OR] = 0.97, 95% confidence interval [CI] 0.86-1.09, P = 0.583; IL-6-IVDD: OR = 1.04, 95% CI 0.86-1.27, P = 0.679; IL-1 α -IVDD: OR = 1.09, 95%CI 1.00-1.18, P = 0.058). However, there was a sign of a connection between genetically elevated IL-1 β levels and a decreased IVDD incidence (OR = 0.87, 95%CI 0.77-0.99, P = 0.03). Our findings suggest a connection between IL-1 β levels and the risk of IVDD. However, due to the support of only one SNP, heterogeneity and pleiotropy tests cannot be performed, the specific underlying mechanisms warrant further investigation.

Causal links between blood inflammation markers and postherpetic neuralgia risk: insights from a two-sample Mendelian randomization study

Introduction

Previous studies have suggested an association between blood inflammation-related factors and postherpetic neuralgia. However, the causal relationship between blood inflammation-related factors and postherpetic neuralgia remains unclear.

Methods

We employed a bidirectional Two-sample Mendelian randomization (MR) analysis to explore the causal relationship between blood inflammation-related factors and postherpetic neuralgia. The instrumental variables were obtained from a large Genome-wide association study (GWAS) meta-analysis dataset of European descent. The instrumental variables of the blood inflammation-related factors come from the database numbers GCST004420 to GCST004460 and GCST90029070. Postherpetic neuralgia has 195,191 samples with a total of 16,380,406 single nucleotide polymorphisms (SNPs). MR analyses were performed using inverse-variance weighted, MR-Egger, and weighted median methods.

Results

The MR results revealed a significant causal effect of Macrophage Inflammatory Protein 1 Beta (MIP1β) on reducing the risk of postherpetic neuralgia (95%CI = 0.492-0.991, p = 0.044). Additionally, higher levels of interleukin (IL)-10 (95%CI = 0.973-0.998, p = 0.019) and IL-12p70 (95%CI = 0.973-0.997, p = 0.013) were associated with a lower risk of postherpetic neuralgia. Other inflammatory markers showed no significant causal relationship with this condition.

Conclusion

This study identifies MIP1β, IL-10, and IL-12p70 as potential therapeutic targets for preventing or treating postherpetic neuralgia, underscoring the need for further research in this area.

Causal associations between frailty and low back pain: a bidirectional two-sample mendelian randomization study

BACKGROUND

Previous observational studies have revealed a potentially robust bidirectional relationship between frailty and low back pain (LBP). However, the precise causal relationship remains unclear.

METHODS

To examine the potential causal association between frailty and LBP, we conducted bidirectional two-sample Mendelian randomization analysis (MR) study. Genetic data on frailty index (FI) and LBP were acquired from publicly available genome-wide association studies (GWAS). Various MR methodologies were utilized, such as inverse variance weighting (IVW), weighted median, and MR-Egger, to evaluate causality. Additionally, sensitivity analyses were conducted to evaluate the robustness of the findings.

RESULTS

Genetically predicted higher FI (IVW, odds ratio [OR] = 1.66, 95% CI 1.17-2.36, p = 4.92E-03) was associated with a higher risk of LBP. As for the reverse direction, genetic liability to LBP showed consistent associations with a higher FI (IVW, OR = 1.13, 95% CI 1.07-1.19, p = 2.67E-05). The outcomes from various MR techniques and sensitivity analyses indicate the robustness of our findings.

CONCLUSION

Our research findings provide additional evidence bolstering the bidirectional causal relationship between frailty and LBP.

Lipid levels and low back pain risk: A two-sample mendelian randomization study

BACKGROUND

Previous observational studies have shown controversial results about the relationship between lipid levels and low back pain (LBP). Herein, we aimed to explore the potential causal relationship between lipid levels and LBP by using the mendelian randomization (MR) analysis.

METHODS

In this two-sample MR study, data were extracted from publicly available MRC Integrative Epidemiology Unit database. Three single-nucleotide polymorphisms (SNPs) of lipid levels [high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), and triglycerides (TG)] and two SNPs of LBP risk (LBP and back pain) were retrieved and used as genetic instrumental variables. Inverse-variance weighted (IVW), weighted median, MR-Egger, robust adjusted profile score (MR-RAPS), and MR-PRESSO were used to examine the potential causal association between lipid levels and LBP.

RESULTS

IVW (fixed effect) estimation indicated that increased HDL-C level was negatively related to the odds of LBP for European populations. [odds ratio (OR) = 0.923, 95% confidence interval (CI): 0.857-0.993, P = 0.0323]. Similar results were also found in IVW (random effect) (OR = 0.923, 95% CI: 0.866-0.983, P = 0.0134), MR-Egger (OR = 0.858, 95%CI: 0.757-0.973, P = 0.0177), MR-RAPS (OR = 0.932, 95%CI: 0.871-0.997, P = 0.0419), and MR-PRESSO (OR = 0.933, 95%CI: 0.880-0.989, P = 0.0198) analyses. Whereas no causal link was observed between LDL-C/TG and LBP risk (P>0.05).

CONCLUSION

This two-sample MR study demonstrated a causal relationship between lipid levels and LBP risk. Further investigations are necessary to elucidate the causal association and specific underlying mechanisms by which lipid levels contribute to the development of LBP.

No evidence for causal effects of C-reactive protein (CRP) on chronic pain conditions: a Mendelian randomization study

Objective

We conducted a Mendelian randomization (MR) study to examine causal associations of C-reactive protein (CRP) with (1) spinal pain; (2) extent of multisite chronic pain; and (3) chronic widespread musculoskeletal pain.

Design

Two-sample MR study.

Setting/Subjects

We used summary statistics from publicly available genome-wide association studies (GWAS) conducted in multiple cohorts and biobanks. Genetic instrumental variables were taken from an exposure GWAS of CRP (n=204,402). Outcome GWASs examined spinal pain (n=1,028,947), extent of multisite chronic pain defined as the number of locations with chronic pain (n=387,649), and chronic widespread pain (n=249,843).

Methods

We examined MR evidence for causal associations using inverse-variance weighted (IVW) analysis and sensitivity analyses using other methods. We calculated odds ratios (ORs), 95% confidence intervals (95% CIs), and p-values, using a Bonferroni correction (p<0.0166) to account for 3 primary comparisons.

Results

Greater serum CRP (mg/L) was not significantly causally associated with spinal pain (OR=1.04, 95% CI 1.00-1.08; p=0.07) in IVW analysis. Greater serum CRP also showed no significant causal association with extent of multisite chronic pain in IVW analysis (beta coefficient= 0.014, standard error=0.011; p=0.19). CRP also showed no significant causal association with chronic widespread pain in IVW analysis (OR=1.00, 95% CI 1.00-1.00; p=0.75). All secondary and sensitivity analyses also showed no significant associations.

Conclusions

This MR study found no causal association of CRP on spinal pain, the extent of chronic pain, or chronic widespread pain. Future studies examining mechanistic biomarkers for pain conditions should consider other candidates besides CRP.

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.

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.

Causal relationships between CD25 on immune cells and hip osteoarthritis

Objectives

Previous research has indicated a potential association between immune factors and osteoarthritis (OA), but the causal relationship between CD25 expression on immune cells and hip OA remains enigmatic. To shed light on this relationship, this study utilized the two-sample Mendelian Randomization (MR) method.

Methods

Leveraging genome-wide association studies (GWAS) data from the UK Biobank and arcOGEN, the investigation encompasses a substantial European cohort comprising 15,704 hip OA cases and 378,169 controls. Genetic insights into CD25 stem from a subgroup of 3,757 individuals with European ancestry, encompassing 77 CD25-related traits. Several MR methods were applied, and robustness was assessed through heterogeneity and sensitivity analysis.

Results

Among the 77 traits examined, 66 shared the same single nucleotide polymorphisms (SNPs) with hip OA. Of these, 7 CD25-related traits were found to be causally associated with hip OA (adjusted P><0.05), with F-statistics ranging from 33 to 122. These traits are specifically related to CD4+CD25+ T cells, exhibiting odds ratios (OR) and 95% confidence intervals (CI) less than 1. Notably, no causal link was discerned with the CD8+CD25+ T cell subset. Within absolute count (AC) and relative count (RC) trait types, a significant causal relationship was observed solely between CD4+CD25+ T cells and hip OA, without subtype localization. A more intricate examination of CD25 expression levels within the CD4+CD25+ T cell subset revealed a correlation with the CD39+ regulatory T (Treg) subset and hip OA, particularly within the CD39+ activated Treg subset. Furthermore, a notable causal relationship emerged between CD25 expression levels in the CD45RA- not Treg subset and hip OA. However, no significant causal link was established with any subsets of B cells.

Conclusion

The genetic prediction suggests that CD25, particularly within the realm of CD4+CD25+ T cells, may exert a protective influence against the development of hip OA. These findings provide a novel therapeutic approach for the prevention and treatment of hip OA.